I think that the bigger issue in full size aircraft is that stiff is heavy. I think the structures/aerodynamics guys would get hold of the aircraft design before the MBAs, and require that the weight be minimized

Regarding the full span ailerons, I think it depends on how you want to fly your plane. If you want a fast "pattern" type plane, then cutting them short probably makes sense. In this case you'll probably be using a high-ish pitch prop, and be doing lots of "horizontal" manuvers.

If you want a slower aircraft with more vertical manuvers, then full span ailerons and a low pitch prop are probably the way to go.

I think it all depends on what kind of flying you want to do with it.

Tom