I'd just go with 2 1450mAh LiPo's - it's not hard to change a battery part way through a day, even if it's a milsim/sim-esque game where going back to the safe zone is either not an option or few & far between, a spare battery isn't much weight to carry...
Well I was under the impression it was ~1 mAh per shot but after chatting to a couple of people this doesn't seem to be the case. I was concerned with 1 battery only being enough for half a box mag.
