Far more important than the capacity of the battery is the quality of the switch and wiring, especially when using any of the 2.4GHz systems. It the wiring between the battery and the receiver has any appreciable impedance, when you draw that momentary rush of current by commanding any high draw servos you will get a voltage drop in that wiring. If it causes the voltage at the receiver bus to drop below the reset (reboot) level, you will get a temporary loss of control. This will happen whether you have a 4.8 or 6 volt battery.