I've spent most of my time over on the toy hauler forum but since we've been talking about moving from the TH to a diesel pusher this is where I'll ask my question. We've been looking at 34 to 36 feet...
I have a 300 Turbo Cat and have been over the Rockies several times and have never found power to be a problem. Just gear down and climb, then gear down and go down. I have never thought I wouldn't get to the top. I have a 37ft DP and up until recently towed a 2001 Honda Odyssey. I bought the coach because I liked the floorplan and price. I never gave thought that it would not have enough power to go where I wanted. Best to you on your search..