I am leaving on a 56 mile hike Aug 13-18 in the High Uintah Wilderness area. I have two sleeping bags and I can't decide which one I should take. The Montbell #0 is a 0-deg rated down bag and weighs 2lbs. 15oz. I can't find an EN rating, but I think the comfort range is around 15-20 degs. My other bag is the Montbell #3. It is a 30-deg bag and weighs 1lb. 9oz. The EN rating is 40 deg comfort, 30 deg lower limit, and 3 deg extreme. I am NOT using a liner, however I am planning to take a set of Thermax thermals. Any suggestions?

The #3 for sure! I have the MB SS#3 and use it for the summer months in Colorado camping up to and over 12,000 ft., and it is fine (I am not a particularly warm sleeper, either). The #0 is way overkill, barring a sudden, extreme weather change. I found it pretty comfortable down to 30 degrees.