For any electrics that do not require lots of current for the servos, the BEC is usually the best choice. However, on large electrics using 4 or more servos or servos drawing high current, the BEC is usually not capable of supplying sufficient power. Then, you must use a seperate receiver battery to power the receiver and servos. When you do this you must also disconnect the red wire from the ESC to the throttle channel on your receiver. As to the Voltwatch, it would only be beneficial when using a seperate battery for the receiver and servos.