RE: the wet down vs. wet poly question

I use a down quilt on river trips. I keep my RayWay quilts around for loaners.

Down comes from geese who are evolved to live on the water in very cold places. Geese don't die from hypothermia. That says something about down; it is very hard to get it wet and functions under wet conditions. As anyone who has ever tried to wash a down garment knows it takes detergent and elbow grease to wet down thoroughly. Then it is a serious job to get all the detergent out. It any remains, the down will wet out more easily - essentially ruined. Soap and detergent remove the oils that keep down dry. That's the best reason to never wash down garments (including sleeping bags). A wipe with rubbing alcohol and a good airing are usually enough anyway.

Polyfill does not provide much insulation when wet. It wets out easily. You can squeeze out all the water you can, but a polyfill bag will still retain a surprising amount adhering to the fibers. Water absorbs a lot of heat. Wrap yourself in a wet polyfill bag and you will expend energy evaporating the remaining water instead of being warm. Under identical circumstances, the down will probably be dry.

On top of all that, down has a wider comfort range than polyfill and doesn't feel clammy inside if things get a little warm. It's also lighter for the same R value, no matter what the marketing department claims.

Down quilts are easy to make, even for a novice. Instructions abound.