I bought a pair of Cabela's Guidewear wading boots with the vibram soles a few weeks ago. I used them a couple of times on the upper Skagit, which I thought was a good test. They performed pretty damned well. Then yesterday I used them on the upper Sky and they were pretty good there too. I had been skeptical of non-felt soles but the last few trips turned me into a believer. Today I fished the NF Stilly and traction was HORRIBLE. I've never slipped around that much. Any rocks I stepped on that were under any amount of water were like wading on greased bowling balls. I fish the Stilly a lot and it's never been tougher wading than other rivers. Out of the places I frequent, the upper Skagit stands out as being the slickest, yet these boots did fine there. I don't know what it is about the north fork, but for some reason the vibram soles on these boots are worthless there. I didn't have a thermometer, but I wonder if the north fork is a touch warmer than the other two rivers and therefore the growing season for river slime starts a little earlier.