I'm considering purchasing a down bag with my REI dividend. I'm currently looking at the Marmot Helium and the Mountain Hardware Phantom 15. Both bags are rated to 15 degrees.
I currently own an REI Shasta 15 degree bag which is 3 lbs 4 oz and has a 9x21 stuff sack. I've used it for a couple of climbing seasons. My main motivations for the down bags are lighter weight and more compressability. My bag takes a lot of space in my (large) multi-day pack (Gregory Shasta), and adds over 3 lbs to an already heavy pack (6+ lbs). I am considering buying a smaller pack for most overnight glacier climbs (as well as day-hikes/scrambles/back country skiing) and a smaller sleeping bag would help make that feasible.
My questions:
1) would it be better to go with a 30 degree bag for shorter trips, or should I stick with a 15 or 20 degree bag - it is the most versatile in the Cascades?
2) How does a 15/20 degree bag fair in cold conditions in Spring and Fall in the Cascades? When / for what climbs would it be insufficient? A winter ascent of Rainier or Baker? How about spring? (I'm considering going up Baker in a couple of weeks)
3) The Helium and Phantom are pretty comparable. The Helium is a bit wider (I am broad-shouldered), but the Phantom has a two-way zipper - good for venting the legs. Anything else people have noticed with either? Good experiences? Bad?
4) I know you don't want to get down wet. This means from the inside as well. How susceptible are these two bags to damp clothing, or breathing into the bag (a no-no?), or sweating?
5) I'm just under 6 feet tall. Is it a good or bad idea to go with a 6'6" bag to leave room for a water bottle or clothes you want to be warm/dry (socks). My synthetic bag is 6', and I don't put much in it with me.
TIA