Having a separate battery for the receiver is certainly not a bad idea, but it probably is not going to make much difference if a servo shorts out and pulls down the servo bus voltage so low, that the good servos can't do the job. Your receiver may be fat and happy, but you're gonna crash anyway
Dirtybird,
Many years ago I had a cell short out in a 4 cell Nicd pack. Those old Airtronics 94102 servos were noticeably sluggish, I landed posthaste!
That's when I switched to 5 cell Nicds. Now I use LiFe/A123 in everything I fly.
Pete