RE: Dual Rates
Sorry, I missed that question. The 549 receiver can have issues with multiple digital servos, a different receiver may help. The 811 however has a single ball bearing on the output gear rather than a dual bearing set up, which allows a little play in the output gear. This play combined with the high performance of the 811 servo with large throws can at times cause some jittering. If you can lightly touch the control surface while this is happening and it stops, it will not cause any problems in the air because the air loads in flight will prevent it from happening.