Last year I switched from a 20deg mummy to the Enlightened Equipment revelation 10deg and I ain't goin back.
Coupled with an Exped downmat 7 UL, it is the most comfortable backcountry sleep I have had.
On 50 degree nights unzip it flat and kick both feet out. On 15 degree nights you zip up the footbox and wear a beanie and some midweights to bed.
Much colder and I would pay closer attention to the stove and wood supply.
