The C++ virtual method call is faster on the Uno than both the switch-case and the function pointer versions. The additional function call and switch-case case processing took a toll for the Uno.

I'm trying to create a "Controllable" interface, that allows a "Controller" object to manipulate the value of generic Controllable objects' variables. Since ...

A C++ function pointer can't. The utility of this should be obvious to anyone who's ever used C++ function pointers only to discover that they can't be used as arbitrary callbacks. More options ...