Great, so stick to the subset of providing a function that asks for a shared_ptr with a shared_ptr instead of introducing unique_ptr as an additional construct.

Great, so stick to the subset of providing a function that asks for a shared_ptr with a shared_ptr instead of introducing unique_ptr as an additional construct. This way you get the benefits of the optimization and don't need to add the overhead of thinking about how shared_ptr will take a unique_ptr and perform a conversion on it. If something takes a foo, give it a foo.