Just as a followup on this - that REI 25F bag was too cold during some nights even on Ilse Royale (windy, 25-30F, high humidity), so after I got back I kept looking for a good deal on that packable 0F bag that was missing in my gear closet.
About two weeks ago I scored a Marmot Couloir 0F on SteepandCheap at 50% off. Very nice bag. About 3 pounds, almost as lofty 800+ fill. Not very roomy, but for the most part it will do the job even in spring in the Sierra. It has a nice long zipper that works so much better than the Mountain Hardwear zipper on my -20F bag ($%@#!!), nice footbox and easy to close hood and draft tube. Love it already. Will test it in April in the Sierra.
