I don't have any gassers at the moment don't have an expectation of getting one for quite a while. But they do seem to be good choices for the usual 1/4 scale WWI fighters. I bought the 6.0V 2000mAh NiMh 5-cell packs a couple of years ago, but have not used them. If and when I get new batteries I'll probably go with the A123 packs (or whatever has supersede that a the battery of choice by that time).
The on-board glow system I got to use with the 770 (Microsens) actually requires its own 3.7V lipo battery (5000mAh). The only suitable battery I could find is the
Turnigy 5000 hardcase which seems like a ridiculous thing to put in a flying model.
Actually, I'm not thinking about flying (or at least testing) the 770 without the on-board system and even the exhaust ring, all of which probably add a full kilo to the weight.