I have been using them for 2 years and hundreds of flights in foamies and other small electrics and slimers without a single failure. I use the 306, 371, 381 and 381MG. I have sold ALOT of these servos and have yet to have a customer complain. While flying in the cold (-20f) I have had GWS and JR servos strip gears INFLIGHT in hard 3D, but not a 306 or 371. I have not used any of the larger servos so I cannot speak for those that are larger than the 381MG.