I've taken my Altitude out on a few trails here in CO as well. I have some scratches that probably cannot be buffed out (I'm not sure though, as I've never had a scratch "fixed" before).
They can definitely climb fairly well, for a 5k lbs, 5 passenger, leather seated, Alpine-audio equipped quasi-luxury ride.
I've bottomed out / hit some stuff underneath a few times which makes me want to add the skid plates, but then again better wheel placement probably would have allowed me to miss those spots anyway.
I upgraded to the stock 20" size in Nitto Terra Grapplers, and I've yet to air-down when on the trail. Not saying it shouldn't be done, just saying that I haven't even gotten to that point. If I start spinning, I usually put it in 4-lo and climb right up. Probably wouldn't need 4-lo if my tires were aired down in the first place.
It is sort of funny seeing peoples' faces when out on the trail though. They'll be in a mid-90's Toyota Tacoma with a roll cage, or a wrangler on 33's, and then I come cruising up with a freshly washed, blacked out, 20" wheel Altitude.
Figured I'd add one of my YouTube videos, where I was only on 2 wheels for a few seconds: