The larger planes might look more intimidating but they are easier to fly. They handle the wind better and are easier to see. The larger wing area also means that the plane can be slowed down and still be very controllable. The high wing bulky shape helps to keep the speed from gettin too high. If you push the sticks too far to the right for example it will take the plane a lot longer to turn completly upside down with a 70" wing span than a plane with a 48" wing span. This is easy to see whats happening on the larger plane and also give you time to realize your mistake and correct it. Thats why the Sig LT40 with the 70" wing span is one of the easiest planes to learn on. IT has decent speed at full throttle but will easily glide well and then land at walking speed.