I'm on my second set of duratracs. My 265/75/16's had 27k miles on them when I sold them back in february and they probably still had another 10k in them. In fact, I saw the guy I sold them to at a stoplight a few weeks ago and he was still riding on them (he commutes 100ish miles a day).
I have 15k on my current set 285/70/17 and they still have a ton of tread left.
Yeah they get a little clogged in the mud, but they're an AT tire, not a MT so naturally they aren't going to perform as well in the mud. Also keep in mind most big heavy full sized trucks have trouble in mud because they're so heavy.
They are awesome tires otherwise, I have taken mine offroad many times, driven in snow and ice on them, they're awesome there too. I commute 50 miles a day on mine.
These will more than likely be what I go with.