I'm in the CO Rockies, and I have problems with plantar fasciitis, so I try to get the stiffest soled boots that I can find. I'm also mega hard on stuff, mileage/terrain-wise.
I've used both the Crispi Altitude and the Kenetrek Mountain Extreme, and I had durability issues with both- the Crispi started breaking threads along the toe cap, and the Kentrek's rubber rand started delaminating the first time I hunted in the rain.
I was able to return the Crispis to Scheels where I'd purchased them in exchange for a store credit (they offered me a new pair, but I didn't want another one given the issue I had).
Kenetrek repaired my first pair of boots, then the repair failed, and now I'm on my second pair that's starting to have the same issue. I'm going to see if they'll repair those so I can keep them as a backup pair.
I just got a pair of Lowa Tibets that I'm hoping will last longer than the others.
Comfort/fit wise, I like the Kenetreks better than the Crispis. I usually wear a D width boot/shoe, and the Crispis were a little narrow for me. The Kenetreks fit a little wider, the sole was stiffer, and they're an inch or so taller. The Lowa Tibets I just got are even a little stiffer and about the same height. I haven't had enough miles on them to speak to their comfort just yet.