Being in the Northern California with my trips being mostly to the Pacific NorthWest, the AC is little more than a boat anchor for me. I do have hopes to travel back East in the future so it stays where it is but it's more of an albatross to me than anything. It sort of ruins the nice lines of the Bigfoot. The couple of times I have used the AC, with the generator it's been for a very short period of time. Maybe 30 minutes tops. It just isn't that cost effective in my opinion and if it is hot out to warrant it, I don't want to risk overheating the generator.
If one did not have anything and was building a system, considering the Lifeline batteries are ~$700, the genset is ~$2500 and paying someone to install all of that could run another $800+, that comes to ~$4000 for batteries and a genset and 300+lbs. Or... Go with 4 of these batteries for 400AH of capacity for roughly the same cost and about 1/3rd the weight.
The cost/benefit ration may not be there quite yet for everyone but if we start getting LiFePos with 100AH for ~$500 they will be very tempting.