I learned to fly rc with a LT40. Full scale in a Piper WarriorII @ Purdue University. I can remember that the Warrior had quit a bit of ground effect sometimes and really wanted to float down the runway. I would think that some of this could carry over to the rc world on low wing aircraft. The main reason for high wing trainers, I think, is mentioned above. The are just more predictable for a newbie to learn on. But to each his own....