I have a pair of Korkers' Guides. The aquastealth soles (without studs) work great on snot-covered rocks and steep, slippery clay-mud banks. In fact, I think the aquastealth soles work better on slippery surfaces than the studded felt boots I previously wore. I fell a few times with my old studded felt boots on the slick clay-mud banks in the area where I currently live. I have not had any problems on those surfaces with the aquastealth. I have not had any need to purchase the studded soles.