I had a GP .40 Cub a number of years ago. It makes a great fun flying airplane with clipped wings. IRC mine had a single servo driving both ailerons but if I were going to do it again I would use a servo for each aileron. I doesn't really need it for aileron authority. With a clipped wing the ailerons cover much of the trailing edge. Although not scale you use mixing in your radio for functional flaps. I can't say that the Cub is likely to need them but that often isn't the point. If you want it, go for it. I enjoyed mine with a .60 four stroke.