i gave up on down some years ago when the poly bags became more
advanced..down is fine for mountain-dry cold but i found that
a couple weeks in canoe country would reduce them to flat
soggy mats..you can never stay in a camp long enought to get them really dry and around the lakes the air is damp all the time..for cold weather camps i put a poly mummy inside a poly
rectangle bag and sleep in soxs and long johns..i know the
folks putting a BOB together will want the lightest warm bag
they can find,but thats my take on sleeping bags..