I totally agree. Just run two batteries into the receiver and take the ignition off of it. This gives redundancy all the way around. I check my packs after every flight, and if one was significantly different you will know there was an issue. So far I've never had an issue. Dual 900's will give you 5 flights comfortably and probably more. The AR70 is a little stiffer so the current draw will be slightly higher, but should still give 5 flights comfortably.

Arch