I had problems with hitec servos in my 8ight 2.0 race roller for some reason. I think I went through 3 of them on throttle. They were cheaper ones that I had left over from old helicopters but I never had any problem with them doing 3D with a 90 size heli. Endpoints were set right and nothing was hitting. One of them quit working before I even ran the buggy. I almost think it had something to do with the DX3S I am using. The servos would work erratic and not have any strength but when I would plug them into an air receiver they would seem to work fine. I put an old slow Futaba 9202 on it and it has been working fine for months now. I know I need to put something better on it but I hate to since it is working so well now.
I also had the stock throttle servo on my wifes 8ight T rtr die after one lap. I took it apart and it even looked cheap inside.