Since this thread has been largely derailed, I just want to pitch in an opinion for the OP.
We've put about 40k on our Vista. It's got the 175 rated T444E and the AT542 (basically at AT545 with a smaller fluid pan). Another Vista owner weighed his empty and it was about 12500, I figure all-in we're adding another 2500 all-in with people and furnishings and food and clothes and cats and our scooter on the back.
Overall it has been a very reliable setup. I've had to replace the alternator (old one fully failed), revamped a large portion of the air conditioners, a glow plug solenoid, and otherwise just normal maintenance. I've been at both temperature extremes, I've been at very high altitudes, I've climbed up and down mountains. It's obviously not a hot rod! If I could get some free HP I'd take it.. but the real limiter seems to be transmission heat. This series of transmission dumps a lot of your power into heat instead of making wheels roll when you're at highway speeds and especially climbing hills. With 1.95 tires and a 4.78:1 rear axle it has a cruising speed just under 60mph, and I believe a lower ratio axle would improve things all around by reducing engine and transmission rpm at highway speed, where both are operating more efficiently. This model uses a split radiator so engine heat and transmission heat are largely combines. Adding a transmission cooler before the main radiator should reduce transmission temperatures significantly as well as help lower engine temps. Heat is what kills both of them!
I absolutely wouldn't flinch about driving across the country again in this bus as it sits today. But horsepower is great and if I can get a bump for nearly free that's a no brainer, but as I mentioned a transmission cooler upgrade would have to go along with it!
