RE: single battery possible?
I have one NiCAD pack and the rest are LiFe.
I figured that current delivery was important very on but simply looking at the impedance of the packs and battery chemistry.
Then observing that most folk having battery trouble used NiMH and those who did not were using LiPo's on regulators.
Where theres smoke there's fire I guess.
Now back to flight packs for gassers. I've still not seen a convincin arguement that running onelarger capacity pack is bad. Failures of LiFe or LiPo packs under low drain is fairly rare I guess but even so they're more robust compared to NiMH.