I've used BA IAC in combination with my BA Horse Thief in my HH on many occasions, generally when there are some chances that I've pushed it too far and want to go to ground in a shelter. That combination with an UQ can almost be overkill unless the temps are below 40 or so. And, as mentioned above, the extra weight (23oz on my mummy, IAC, I think) doesn't make it worth it.
It is nice for extra insurance, as I've had some cold nights while I was figuring out what worked and what didn't.
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