For those who are actually going to use the 8611 or similar servos.
The performance of these is seriously influenced by the power available to them.
It is a MUST, to have a battery setup which will not "droop" when the servos are operating under flight loads.
Use a 6 V high amperage potential, set of batteries - multiple power inputs, power distributors, dual switches, etc., which are designed to transport the current needed for these servos.
There is a BIG difference in performance .
Just adding the high performance servo is of little or no added performance value.