RE: single battery possible?
I have my 30cc Yak setup with dual 1100 A123 packs and separate switches to the receiver, ignition is powered from the receiver by a Wike IBEC. I've never used 50% of the capacity of the packs.
I have an old Goldberg Extra 300 (BIY kit) with a 20cc and run just a single 2300mAh A123 pack for receiver and ignition. Never a problem. As I understand it, the lower the internal resistance of the battery, the more it acts as a filter to any voltage spikes.
For any size glow powered model, even a .90 or better, just pop in a 2S A123 pack of 1100mAh and go fly[8D]
Pete