Ok, if you are going to get a low powered down bag, save yourself the agony of a crappy bag from some 2nd rate company like REI and get a good synthetic bag that will weigh the same and cost the same.
REI bags, lose their loft quickly I have found compared to other manufacturers. 3 different REI bags over the years between myself, my brother, father, and friends. Yes, had several hanging in the closet just like my Marmot and Feathered Friends. Well my bros anyways. Bought same time. Used my other NON REI down bags for around 400 days sleeping in said bag and they still have far more loft after 20 years. The REI bag was dead at 10 due mostly to the fact that all of the down over the chest area seemed to "vanish". Same with the foot area. Maybe they have started building better bags, but since it says REI on the side, I doubt it. Their clothes seem to be fine though.
I would get a Synthetic 4lb bag from Patagonia, North Face, Marmot, before throwing money down the drain on a 600 down synthetic sleeping bag from some hack job company like REI who counts on selling to the general public who never uses their gear but once or twice a year at most. IE they can claim it "lasts" a long time to the general goes nowhere public. Off hand, I bet that most who read this forum are Not such folks.
4lb down bag or 4lb synetheic bag. Get the 4lb synthetic bag everytime. Will dry out faster if the Fhit hits the San. Only reason to get down is that for same rating it is lighter. If its a toss-up, its a no brainer generally speaking. Though senthetics traditionally do not keep their loft as long as down. Not sure about the newest polarguards etc.
