OPC, I didn't know you fought fire in the 90s.
I've spent a few nights in those bags on fires. When dry, they have more insulation value than a poncho, not as much as a poncho liner let alone a quilt or poncho liner made out of modern materials. They were pretty bulky too. It's been a lot of years, but I seem to remember a roll about a foot in diameter and 14" long. They were pretty light by the standards of the day, but at least a couple of pounds. A DWR shelled primaloft quilt or poncho liner beats those paper bags by a pretty fair margin in every way I can think of.
Sometimes I play the "how would I outfit myself these days if I was still a hotshot" game. For the weight of the GI poncho I used to carry, I could have a silnylon poncho AND a modern synthetic poncho liner.
