I have a Hitec 615 metal gear, on the rudder, 605's on the elevators, & a 422 on each aileron. Only rudder is M/G. I have 70+ flights with a FPE 2.4, and absolutly zero problems with palne, motor or radio gear. I dont fly 3D, but I sure dont fly strait & level either. Do definately us 4 servos on ailerons though. Will reduce the chances of flutter, and flutter will destroy the best of servos eventually.