So I've been running these tires for two years now and have approximately 30k miles on them both on and off road. I'm running a 275/70r18 with the stock 7.5 inch wide rims at about 28psi on road and 15psi off road. The have been a very good all around tire.
They are acceptable in the winter, not as good as my Blizzaks, but what is? They have also been admirable in the Alaskan mix of mud, rocks, and gravel. They do pack up a little with mud, but easily spin clean and grip. I've managed to put some pretty good rock scars in my stock wheels, but haven't even scratched the tire sidewalls. I have enough confidence in them that I usually run either as the lead rig or as cleanup on group rides.
They have gotten louder as they wear in, and are now starting to approach a noticeable hum. Not bad, but definitely present. Without measuring the tread depth, I'd estimate another 15-20k miles of life remaining in them. I'm caught in the proverbial catch 22 of wanting to go with bigger tires, but mine are still in good shape.
For comparison, I've run the old BFG KOs, BFG Rugged Terrains, Nitto Terra Grapplers, and Goodyear Duratracs. The Duratracs are a better winter tire, but not enough to make me switch and I prefer the Cooper's stronger sidewalls. The old KOs were unimpressive, especially in winter and in mud as were the Nittos.
They will likely be my next tire, although I do want to see the new Cooper STT Pros that were reviewed by Scott. However, the tread pattern on the Pro doesn't seem to be as suitable for winter driving as the Maxx.
Mike