On warm days, I use my bag open, like a quilt, but on cold days, I really appreciate being able to zip it up. I upgraded to a Versatile bag in Mammoth - which has the best zipper ever,
I got an envelope for my sleeping pad from the DownWorks in Santa Cruz, which gives me more room like a quilt, but it has zippers on both sides, so I can choose to unzip 1 or both sides on warm days.
For me, on the JMT, I was cold my first week from TM to Mammoth with a 20 degree synthetic bag. This was the end of August ¡ª and it got colder as I went up in elevation further south. I was very glad that I got a new down bag in Mammoth - even though it cost me a small fortune, even on sale.
Linda Selover
Stormy2007@...
Linda