Larry, you can wring it out and it will retain your body heat better than anything else when wet. I use nothing but wool gloves for that reason. People say that about wool because it's true. I once managed to pull myself off the front of a flatbottomed boat while duck hunting, trying to scull past a stob and avoid a blowdown. There was skim ice on the river, but fortunately I was wearing a thick wool sweater. I made the rest of the float trip in reasonable comfort. I don't think I was in the water more than two seconds, but it was enough!
I like down too, usually under something else. I have much better freedom of movement with a down vest when it's really cold, as opposed to a full insulated coat. I'll carry it to my stand, though, to keep from overheating on the way. Like others have said, it takes up practically no space and has negligible weight.