Always preferred Futaba servos myself as I have seen one too many JR servos suddenly lock up and cause a crash. Having said that, there are so many people in my area successfully using JR servo so I know they are fine. For Futabas, I would use a 9154 or 9150 digital or 9102 analog servos for ailerons, 9650s for dual elevators or 9151, 9255, 9252 for single elevators (9402, 9404,9204or 9206 if analog), 9255, 9350, 9151 for rudder (9204, 9402, 9206 for analog). ALL Futaba servos rated at 4.8 volt can safely run with no problem at 6 volts regulated since a freshly charged 4 cell battery would exceed 6 volts. They cannot be run at 6 volts unregulated since a freshly charged 5 cell battery would exceed 7 volts. I have been running these 4.8 volt rated Futaba servos with a 5 cell battery and 6 volt Jaccio regulators for the past 10 years in over a dozen 2x2 pattern planes with not a single problem so you can still get some free torque and speed with Futaba. Just my humble opinion based on my experiences.