I'm also a vest wearer. I have a Western Mountaineering down version that squeezes down about the size of a softball and weighs almost nothing. And somehow, under my rain jacket/wind shirt, it keeps me warm enough down to about freezing, and a bit further when I'm wearing my silk longies. And, yeah, I also wear it under the poncho, and the no sleeves to get wet is indeed handy. Hadn't thought of it that way, but yes. Thanks, Samoset. Best, jcp