I think I can answer this question. I am a side sleeper and a flopper. I go constantly from one side to the other. I keep my bag in one place and move inside of it. This is mainly because I put my "pillow" in the bottom so if the bag rolls the pillow is on my head rather than under it. This also keeps the opened part of the bag up so that I get good air flow.

As for the loft, I believe it is measured from the gound to the top (both layers). However, I am not positive on that.

ken
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Just an old newbe