I know from building and flying giant scale planks for years that multiple servos, working under heavy flight loads can place momentary amperage loads on the battery of as much as 1.5 to 2 AMPS. That's why we often use huge battery packs, dual receivers and power busses.
I had a friend crash his newly rebuilt, (1st flight), JR Ergo .60 for no apparent reason. There was no glitch, just sudden and total loss of the radio link. It happened as he came out of a high banked, moderate G-force turn. When we picked up the remains, we could find nothing that would indicate what caused the crash. And, battery voltage read 5.2V.
My theory is that he had a bad battery pack, (bad cell or cells), and all those digitals and gyro working under load, caused a spike in the current draw that dropped the voltage so low, the system failed. He was flying with an 1800mAh pack. During testing, when he loaded it with 1.2 AMPs or better, the voltage immediately dropped from 5.4V to almost zero.
So, my question is, how much of a "spike" load should any given freshly charged 4.8V battery pack be able to pull before the current draw pulls the voltage under what you might call "critical voltage", 4.4V? I would think that a pack should stand up under a short term load equal to it's capacity without dropping the voltage below 4.4V.