I bought a K60 scout set for a trip this month and have about 2500 miles on them now. The front shows very little wear and the back looks used. The tires have seen dry and rain paved roads and dry, rain, hail, and snow off road. 2000 miles have been on the road and about 500 off road. Off road includes fire roads and rocky terrain. The only time I had problems was in the snow and ice, but I think most duel purpose tires would have a problem there too. Below are a couple pics of mid trip. I leave again tomorrow to head out on the last part of my trip which will add about another 1000 miles to the tires. They really don't seem to be wearing that fast and the only thing I would possibly do different is put a TKC80 on the front for some better off road performance (the K60 front tends to "slide" if not careful). These also seem grip very well on the road. I did some rides around the mountains in the denver area with my brother on the street and was very comfortable leaning the bike over and not worrying about them breaking loose.
edited: I have been using these tires with a loaded down bike. Both side BMW side cases full, a dry bag of clothes on the back seat, and a trunk of misc (camera, notepad, sleeping bag, extras gloves, and rain gear). Basically they have been holding up very well with some weight on them.