I've got 370 flights now on the BobCat with 3421's on both the rudders and elevators. However, with what we have seen, I would not recommend using them on the rudders now. I don't plan to change mine, but if I built a new BC I would install 9411's on the rudders. My next BC may very well have a single 8411 on the elevator, just to make it simpler. It's also a bit more precise servo.

Another point, my BC is a standard with a 500, so it may not be seeing the loads of the 120/1000/180 powered BC's out there. Must be some reason why my 3421's just keep ticking.