Thought i would put my two cents in here, before my wife and i decided on the Gateway we looked at alot of other fw's, so many at times i couldn't remember which was which or what had what, when we got to the short list we had a Big Country and Gateway on it along with another manufacture, anyway we finaly made our decision on price point and options, the Gateway had more std options than any other fw we looked at, the BC could be ordered with extras but raised cost.
As far as insulation, alot of you know we were stuck in Spokane last winter through some extremely cold temps and the Gateway was more than adequetly insulated, sub zero for almost two weeks, inside was fine, propane usage not bad considering were were heating water as well as using the furnace and stove, 3-4 days per tank. The low drains were the weak link for cold weather camping and some help from others got me up and out of trouble there.
I think any rv would have issues in the weather we went through but the Gateway was more than impressive. I wouldn't hesitate to full time it in this rv in any weather now. As far as temps in summer the dual ac's keep the fw very comfortable, that was an option on the BC
