RE: pros &cons of using 4. 8 or 6 volt for rx
I have never used a 6V RX battery either. From what little i do know it's my understanding that the quicker response and higher tork from the servo's is a good thing as they need instant response for 3D style flying.
For scale type flying in say a Piper Cub/Cessna/P-40 type planes you don't need that as you want smooth gentle flight as your not going to be yanking on the stick's at all.
I have also read but dont know from direct experience that a 6V RX battery will potentially require you to use bigger battery/servo leads because it is driving the servos harder and using more amp's then a 4.8V pack will,,,,And sense it's using more current the flight time is not any greater and could be worse then a 4.8V pack.
I do know from experience that 4.8V works just great in my planes and i get about 4 flight's on a 1500mah pack running 9 servo's None of them are 3D planes though.
Pat