First some background. I am the coldest sleeper in the known universe. I am 55+ years old and skinny as a rail with no body fat, and when I go to sleep, my metabolism apparently just shuts off.
At this point in time I am sleeping on an Exped 7 downmat. I say this, so people can jump in on this thread and tell me what a wuss I am. At my advanced age and skinny as I am, my unpadded bones need the help to get a decent nights sleep. Not only that, this thing is warm in the warmest possible way. Yeah, baby! This is one area where my ultralight gear has swung back to the "heavier is OK, cause I need a good nights sleep" way of thinking. Closed cell foam will only work for me if I am sleeping in a sandy desert wash. A full up thermarest doesn't cut it for me on anything resembling hard ground.
OK, now for the real questions. My current sleep options are a 35 degree rated "Big Agnes Horse Thief" that weighs 31 ounces and will keep me warm down to like 50 degrees (me that is). So to stay warm, I add "pajamas" in the form of the warmest available capilene (which for tops and bottoms adds 24 ounces, for a total of 55 ounces), and keeps me warm down to 35 degrees.
With this setup at 22 degrees, I froze my rear end off.
The second option is a very nice 15 degree rated Marmot Pinnacle down bag, which weighs 52 ounces, this would allow me to leave the "pajamas" at home, for a net savings of 3 ounces. Hmmmm.
I have been admiring the Rocky Mountain Sniveller Quilt (a mere 28 ounces in the long form I would need), but thought I would post and troll for suggestions on the next step toward achieving greater sleeping warmth with a greater weight savings. The dual use "wear it around camp" idea sounds like a great bonus. But maybe there are other things to consider, and that is where you, dear reader, can come in!

