I sold off my stock KO2's and put on 255/80R17 Falken AT4/W and I am very happy.
Pros:
* on wet roads and snow I likely have better traction and braking than if I went wider
* quieter (maybe better fuel economy?)
* bonus: steering effort & return-to-centre is noticeably better
Neutral:
* offroad, I did a long day of skills training with the tires, climbing dry dirt and rocks, and never once felt I "needed" anything wider
* you get the same clearance gain over stock (a little over half an inch) whether you go up to 255/80R17 or up to 285/70R17
Cons:
* I may be worse off in some muddy conditions, maybe (but I don't want a mud tread pattern, which is really what's needed)
Honestly, it's probably splitting hairs. Get what makes you smile and wear them out!