Sorry if this is too frequent a topic for your tastes, the searches weren't really turning up what I want.
Just a bit of background first: I'm probably what you'd call a hot sleeper. I did most of the AT with a silk liner and a microfleece blanket. I used a North Face Kilo 30F bag for the spring (April 18 start) and fall (got it again after Massachusetts). It was sufficient for the most part, but I couldn't stand it zipped up - too tight around the chest, arms couldn't move, etc. I don't know if I'd really like any mummy, but this bag was way too skinny from the waist up. Temperature-wise it was only uncomfortable for bits of the Smokies and Maine when temps got down into the 20's, and that was with a down jacket added into the mix.
I'm now looking at a summertime hike on the PCT, and I'd like a lighter bag that is also warmer. Not asking much, I know. At 2lb6oz the Kilo is a bit heavier than it needs to be for the warmth. I see it as a 40 degree bag, really - especially since I can't zip it up or even consider cinching the hood. Right now I'm thinking about the Marmot Hydrogen (30F) and the Montbell UL super Spiral #3, but these would both be big investments and there aren't outfitters that carry them nearby so I can't even test them out. How roomy is the Hydrogen? Does the Montbell stretch fabric make it more comfortable or more claustrophobic? Would I be better off looking at a semi-rectangular bag or even a quilt, since I can't seem to get the hang of the a mummy? Or was that just due to my North Face bag's narrow cut?