Brenner

If you are flying electric (which I think you are) you can drop your Rx pack to a 2s 480 lipo which will be good for 5 flights easily. Even with the extra weight of a regulator I think you will be ahead in weight from the 1100 a123. Figure about 40 grams or so for the 480+reg, the 1100 a123 cells are 40g each, so you are at least 80g + wrapping and cables.