diff --git a/docs/src/backend.md b/docs/src/backend.md
index 35637a64..0af1a039 100644
--- a/docs/src/backend.md
+++ b/docs/src/backend.md
@@ -96,26 +96,27 @@ nlp = ADNLPModel(f, x0)
 get_adbackend(nlp) # returns the `ADModelBackend` structure that regroup all the various backends.
 ```
 
-There are currently two ways to modify instantiated backends. The first one is to instantiate a new `ADModelBackend` and use `set_adbackend!` to modify `nlp`.
+To instantiate a new `ADModelBackend` while preserving existing backends, use `set_adbackend`.
 
 ```@example adnlp2
 adback = ADNLPModels.ADModelBackend(nlp.meta.nvar, nlp.f, gradient_backend = ADNLPModels.ForwardDiffADGradient)
-set_adbackend!(nlp, adback)
-get_adbackend(nlp)
+new_nlp = set_adbackend(nlp, adback)
+get_adbackend(new_nlp)
 ```
 
-The alternative is to use `set_adbackend!` and pass the new backends via `kwargs`. In the second approach, it is possible to pass either the type of the desired backend or an instance as shown below.
+An alternative way to use `set_adbackend` is to pass the new backends as keyword arguments.
+In this approach, you can pass either the type of the desired backend or an existing instance, as shown below.
 
 ```@example adnlp2
-set_adbackend!(
+new_nlp = set_adbackend(
   nlp,
   gradient_backend = ADNLPModels.ForwardDiffADGradient,
   jtprod_backend = ADNLPModels.GenericForwardDiffADJtprod(),
 )
-get_adbackend(nlp)
+get_adbackend(new_nlp)
 ```
 
-### Support multiple precision without having to recreate the model
+### Multi-precision model creation with backend reuse
 
 One of the strength of `ADNLPModels.jl` is the type flexibility. Let's assume, we first instantiate an `ADNLPModel` with a `Float64` initial guess.
 
@@ -133,11 +134,11 @@ x64 = rand(2)
 grad(nlp, x64)
 ```
 
-It is now possible to move to a different type, for instance `Float32`, while keeping the instance `nlp`.
+It is now possible to move to a different type for the gradient, for instance `Float32`, while keeping the other backends from the original model `nlp`.
 
 ```@example adnlp3
 x0_32 = ones(Float32, 2)
-set_adbackend!(nlp, gradient_backend = ADNLPModels.ForwardDiffADGradient, x0 = x0_32)
+new_nlp = set_adbackend(nlp, gradient_backend = ADNLPModels.ForwardDiffADGradient, x0 = x0_32)
 x32 = rand(Float32, 2)
-grad(nlp, x32)
+grad(new_nlp, x32)
 ```
diff --git a/src/ADNLPModels.jl b/src/ADNLPModels.jl
index a50d1005..6cb9fa84 100644
--- a/src/ADNLPModels.jl
+++ b/src/ADNLPModels.jl
@@ -160,7 +160,7 @@ function ADNLSModel!(model::AbstractNLSModel; kwargs...)
   end
 end
 
-export get_adbackend, set_adbackend!
+export get_adbackend, set_adbackend
 
 """
     get_c(nlp)
@@ -244,22 +244,24 @@ Returns the value `adbackend` from nlp.
 get_adbackend(nlp::ADModel) = nlp.adbackend
 
 """
-    set_adbackend!(nlp, new_adbackend)
-    set_adbackend!(nlp; kwargs...)
+    new_nlp = set_adbackend(nlp, new_adbackend)
+    new_nlp = set_adbackend(nlp; kwargs...)
 
-Replace the current `adbackend` value of nlp by `new_adbackend` or instantiate a new one with `kwargs`, see `ADModelBackend`.
-By default, the setter with kwargs will reuse existing backends.
+Create a copy of nlp that replaces the current `adbackend` with `new_adbackend` or instantiate a new one with `kwargs`, see `ADModelBackend`.
+By default, the setter with keyword arguments will reuse existing backends.
 """
-function set_adbackend!(nlp::ADModel, new_adbackend::ADModelBackend)
-  nlp.adbackend = new_adbackend
-  return nlp
+function _set_adbackend(nlp::ADM, new_adbackend::ADModelBackend) where{ADM}
+  values = [f == :adbackend ? new_adbackend : getfield(nlp, f) for f in fieldnames(ADM)]
+  base_type = Base.typename(ADM).wrapper
+  return base_type(values...)
 end
-function set_adbackend!(nlp::ADModel; kwargs...)
+
+function _set_adbackend(nlp::ADModel; kwargs...)
   args = []
   for field in fieldnames(ADNLPModels.ADModelBackend)
     push!(args, if field in keys(kwargs) && typeof(kwargs[field]) <: ADBackend
       kwargs[field]
-    elseif field in keys(kwargs) && typeof(kwargs[field]) <: DataType
+    elseif field in keys(kwargs) && kwargs[field] <: ADBackend
       if typeof(nlp) <: ADNLPModel
         kwargs[field](nlp.meta.nvar, nlp.f, nlp.meta.ncon; kwargs...)
       elseif typeof(nlp) <: ADNLSModel
@@ -269,8 +271,8 @@ function set_adbackend!(nlp::ADModel; kwargs...)
       getfield(nlp.adbackend, field)
     end)
   end
-  nlp.adbackend = ADModelBackend(args...)
-  return nlp
+  new_nlp = set_adbackend(nlp, ADModelBackend(args...))
+  return new_nlp
 end
 
 end # module
diff --git a/src/forward.jl b/src/forward.jl
index 2a3d35b7..64c29821 100644
--- a/src/forward.jl
+++ b/src/forward.jl
@@ -4,8 +4,8 @@ function gradient!(::GenericForwardDiffADGradient, g, f, x)
   return ForwardDiff.gradient!(g, f, x)
 end
 
-struct ForwardDiffADGradient <: ADBackend
-  cfg
+struct ForwardDiffADGradient{GC} <: ADBackend
+  cfg::GC
 end
 function ForwardDiffADGradient(
   nvar::Integer,
@@ -109,7 +109,7 @@ function GenericForwardDiffADJtprod(
   return GenericForwardDiffADJtprod()
 end
 function Jtprod!(::GenericForwardDiffADJtprod, Jtv, f, x, v, ::Val)
-  Jtv .= ForwardDiff.gradient(x -> dot(f(x), v), x)
+  ForwardDiff.gradient!(Jtv, x -> dot(f(x), v), x)
   return Jtv
 end
 
diff --git a/src/nlp.jl b/src/nlp.jl
index 37315c24..12f28f87 100644
--- a/src/nlp.jl
+++ b/src/nlp.jl
@@ -1,18 +1,18 @@
 export ADNLPModel, ADNLPModel!
 
-mutable struct ADNLPModel{T, S, Si} <: AbstractADNLPModel{T, S}
+mutable struct ADNLPModel{T, S, Si, F1, F2, ADMB <: ADModelBackend} <: AbstractADNLPModel{T, S}
   meta::NLPModelMeta{T, S}
   counters::Counters
-  adbackend::ADModelBackend
+  adbackend::ADMB
 
   # Functions
-  f
+  f::F1
 
   clinrows::Si
   clincols::Si
   clinvals::S
 
-  c!
+  c!::F2
 end
 
 ADNLPModel(
@@ -127,7 +127,7 @@ function ADNLPModel(f, x0::S; name::String = "Generic", minimize::Bool = true, k
   meta =
     NLPModelMeta{T, S}(nvar, x0 = x0, nnzh = nnzh, minimize = minimize, islp = false, name = name)
 
-  return ADNLPModel(meta, Counters(), adbackend, f, x -> T[])
+  return ADNLPModel(meta, Counters(), adbackend, f, (c, x) -> similar(S, 0))
 end
 
 function ADNLPModel(
@@ -157,7 +157,7 @@ function ADNLPModel(
     name = name,
   )
 
-  return ADNLPModel(meta, Counters(), adbackend, f, x -> T[])
+  return ADNLPModel(meta, Counters(), adbackend, f, x -> similar(S, 0))
 end
 
 function ADNLPModel(f, x0::S, c, lcon::S, ucon::S; kwargs...) where {S}
@@ -222,8 +222,7 @@ function ADNLPModel(
   ucon::S;
   kwargs...,
 ) where {S}
-  T = eltype(S)
-  return ADNLPModel(f, x0, clinrows, clincols, clinvals, x -> T[], lcon, ucon; kwargs...)
+  return ADNLPModel(f, x0, clinrows, clincols, clinvals, x -> similar(S, 0), lcon, ucon; kwargs...)
 end
 
 function ADNLPModel(
@@ -339,7 +338,6 @@ function ADNLPModel(
   ucon::S;
   kwargs...,
 ) where {S}
-  T = eltype(S)
   return ADNLPModel(
     f,
     x0,
@@ -348,7 +346,7 @@ function ADNLPModel(
     clinrows,
     clincols,
     clinvals,
-    x -> T[],
+    x -> similar(S, 0),
     lcon,
     ucon;
     kwargs...,
diff --git a/src/nls.jl b/src/nls.jl
index 8484479a..34d6ebe0 100644
--- a/src/nls.jl
+++ b/src/nls.jl
@@ -1,19 +1,19 @@
 export ADNLSModel, ADNLSModel!
 
-mutable struct ADNLSModel{T, S, Si} <: AbstractADNLSModel{T, S}
+mutable struct ADNLSModel{T, S, Si, F1, F2, ADMB <: ADModelBackend} <: AbstractADNLSModel{T, S}
   meta::NLPModelMeta{T, S}
   nls_meta::NLSMeta{T, S}
   counters::NLSCounters
-  adbackend::ADModelBackend
+  adbackend::ADMB
 
   # Function
-  F!
+  F!::F1
 
   clinrows::Si
   clincols::Si
   clinvals::S
 
-  c!
+  c!::F2
 end
 
 ADNLSModel(
diff --git a/src/reverse.jl b/src/reverse.jl
index a21e04ca..5ae23ec6 100644
--- a/src/reverse.jl
+++ b/src/reverse.jl
@@ -7,8 +7,8 @@ end
 struct GenericReverseDiffADJprod <: ADBackend end
 struct GenericReverseDiffADJtprod <: ADBackend end
 
-struct ReverseDiffADGradient <: ADBackend
-  cfg
+struct ReverseDiffADGradient{GC} <: ADBackend
+  cfg::GC
 end
 
 function ReverseDiffADGradient(
diff --git a/test/Project.toml b/test/Project.toml
index e6ae782e..d894d281 100644
--- a/test/Project.toml
+++ b/test/Project.toml
@@ -1,5 +1,6 @@
 [deps]
 ForwardDiff = "f6369f11-7733-5829-9624-2563aa707210"
+JET = "c3a54625-cd67-489e-a8e7-0a5a0ff4e31b"
 LinearAlgebra = "37e2e46d-f89d-539d-b4ee-838fcccc9c8e"
 ManualNLPModels = "30dfa513-9b2f-4fb3-9796-781eabac1617"
 NLPModels = "a4795742-8479-5a88-8948-cc11e1c8c1a6"
@@ -12,6 +13,7 @@ Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"
 
 [compat]
 ForwardDiff = "0.10"
+JET = "0.9, 0.10"
 ManualNLPModels = "0.1"
 NLPModels = "0.21"
 NLPModelsModifiers = "0.7"
diff --git a/test/enzyme.jl b/test/enzyme.jl
index a844166e..a0bed47a 100644
--- a/test/enzyme.jl
+++ b/test/enzyme.jl
@@ -1,4 +1,5 @@
 using LinearAlgebra, SparseArrays, Test
+using JET
 using SparseMatrixColorings
 using ADNLPModels, ManualNLPModels, NLPModels, NLPModelsModifiers, NLPModelsTest
 using ADNLPModels:
diff --git a/test/nlp/basic.jl b/test/nlp/basic.jl
index 07c4d940..37bbbe3f 100644
--- a/test/nlp/basic.jl
+++ b/test/nlp/basic.jl
@@ -25,7 +25,7 @@ function test_autodiff_model(name; kwargs...)
   @test abs(obj(nlp, β) - norm(y .- β[1] - β[2] * x)^2 / 2) < 1e-12
   @test norm(grad(nlp, β)) < 1e-12
 
-  test_getter_setter(nlp)
+  test_allocations(nlp)
 
   @testset "Constructors for ADNLPModel with $name" begin
     lvar, uvar, lcon, ucon, y0 = -ones(2), ones(2), -ones(1), ones(1), zeros(1)
diff --git a/test/nls/basic.jl b/test/nls/basic.jl
index 31ae2539..9d40cc9d 100644
--- a/test/nls/basic.jl
+++ b/test/nls/basic.jl
@@ -5,7 +5,7 @@ function autodiff_nls_test(name; kwargs...)
 
     @test isapprox(residual(nls, ones(2)), zeros(2), rtol = 1e-8)
 
-    test_getter_setter(nls)
+    test_allocations(nls)
   end
 
   @testset "Constructors for ADNLSModel" begin
diff --git a/test/runtests.jl b/test/runtests.jl
index 44ccce21..0b233c0e 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -1,5 +1,6 @@
 using LinearAlgebra, SparseArrays, Test
 using SparseMatrixColorings
+using ForwardDiff, JET
 using ADNLPModels, ManualNLPModels, NLPModels, NLPModelsModifiers, NLPModelsTest
 using ADNLPModels:
   gradient, gradient!, jacobian, hessian, Jprod!, Jtprod!, directional_second_derivative, Hvprod!
diff --git a/test/utils.jl b/test/utils.jl
index 7246354b..a47f9fb3 100644
--- a/test/utils.jl
+++ b/test/utils.jl
@@ -1,36 +1,19 @@
-ReverseDiffAD(nvar, f) = ADNLPModels.ADModelBackend(
-  nvar,
-  f,
-  gradient_backend = ADNLPModels.ReverseDiffADGradient,
-  hprod_backend = ADNLPModels.ReverseDiffADHvprod,
-  jprod_backend = ADNLPModels.ReverseDiffADJprod,
-  jtprod_backend = ADNLPModels.ReverseDiffADJtprod,
-  jacobian_backend = ADNLPModels.ReverseDiffADJacobian,
-  hessian_backend = ADNLPModels.ReverseDiffADHessian,
-)
+function test_allocations(nlp::ADNLPModel)
+  x = nlp.meta.x0
+  y = zeros(eltype(nlp.meta.x0), nlp.meta.ncon) 
+  g = zeros(eltype(nlp.meta.x0), nlp.meta.nvar)
+  @test_opt target_modules=(ADNLPModels,) obj(nlp, x)  
+  @test_opt target_modules=(ADNLPModels,) cons!(nlp, x, y)
+  @test_opt target_modules=(ADNLPModels,) grad!(nlp, x, g)
+end
 
-function test_getter_setter(nlp)
-  @test get_adbackend(nlp) == nlp.adbackend
-  if typeof(nlp) <: ADNLPModel
-    set_adbackend!(nlp, ReverseDiffAD(nlp.meta.nvar, nlp.f))
-  elseif typeof(nlp) <: ADNLSModel
-    function F(x; nequ = nlp.nls_meta.nequ)
-      Fx = similar(x, nequ)
-      nlp.F!(Fx, x)
-      return Fx
-    end
-    set_adbackend!(nlp, ReverseDiffAD(nlp.meta.nvar, x -> sum(F(x) .^ 2)))
-  end
-  @test typeof(get_adbackend(nlp).gradient_backend) <: ADNLPModels.ReverseDiffADGradient
-  @test typeof(get_adbackend(nlp).hprod_backend) <: ADNLPModels.ReverseDiffADHvprod
-  @test typeof(get_adbackend(nlp).hessian_backend) <: ADNLPModels.ReverseDiffADHessian
-  set_adbackend!(
-    nlp,
-    gradient_backend = ADNLPModels.ForwardDiffADGradient,
-    jtprod_backend = ADNLPModels.GenericForwardDiffADJtprod(),
-  )
-  @test typeof(get_adbackend(nlp).gradient_backend) <: ADNLPModels.ForwardDiffADGradient
-  @test typeof(get_adbackend(nlp).hprod_backend) <: ADNLPModels.ReverseDiffADHvprod
-  @test typeof(get_adbackend(nlp).jtprod_backend) <: ADNLPModels.GenericForwardDiffADJtprod
-  @test typeof(get_adbackend(nlp).hessian_backend) <: ADNLPModels.ReverseDiffADHessian
+function test_allocations(nlp::ADNLSModel)
+  x = nlp.meta.x0
+  y = zeros(eltype(nlp.meta.x0), nlp.meta.ncon) 
+  g = zeros(eltype(nlp.meta.x0), nlp.meta.nvar)
+  Fx = zeros(eltype(nlp.meta.x0), nlp.nls_meta.nequ)
+  @test_opt target_modules=(ADNLPModels,) function_filter=(@nospecialize(f) -> f != ForwardDiff.gradient!) obj(nlp, x)  
+  @test_opt target_modules=(ADNLPModels,) function_filter=(@nospecialize(f) -> f != ForwardDiff.gradient!) cons!(nlp, x, y)
+  @test_opt target_modules=(ADNLPModels,) function_filter=(@nospecialize(f) -> f != ForwardDiff.gradient!) grad!(nlp, x, g, Fx)
+  @test_opt target_modules=(ADNLPModels,) function_filter=(@nospecialize(f) -> f != ForwardDiff.gradient!) residual!(nlp, x, Fx)
 end
diff --git a/test/zygote.jl b/test/zygote.jl
index 023c217d..e8a28a52 100644
--- a/test/zygote.jl
+++ b/test/zygote.jl
@@ -1,4 +1,5 @@
 using LinearAlgebra, SparseArrays, Test
+using JET
 using ADNLPModels, ManualNLPModels, NLPModels, NLPModelsModifiers, NLPModelsTest
 using ADNLPModels:
   gradient, gradient!, jacobian, hessian, Jprod!, Jtprod!, directional_second_derivative, Hvprod!