Some good info so far ... I've owned 3 Montana's over the years as well as a Brand "X" or two. Two things stand out over my 24 years of RV ownership.
1. All manufacturers advertisement of "4 Season" cannot be compared to your experience in your stick house. You can only install so much insulation in a 2" wall or a 7/16" slide out floor. Dual pane glass helps immensely (IMHO) over the standard glass that has a lot of acreage on about any RV. RV's will not compare in the higher and lower temps, but that should be easily figured out.
2. What some responders definition of "comfortable" is on any RV website may be a long ways from your definition. Some feel 50's to 60's in winter is optimal ... for us, in that environment, I would be going to the "Big D" and I don't mean Dallas.
