Devo7-Servo problems

Have 2 Devo7's, 2 Master CP's, and a SuperCP. Servos jitter and lag badly on all 3 heli's. Tried both transmitters, one is far worse than the other. Leading me to believe it's in the TX. Is it an adjustment or just bad transmitters? Would I just be better off buying a Devo7e or a 10?