You’re up against the laws of physics on this one, Dan. Any sole that has any chance to grip wet surfaces would have to be extremely soft. And the problem with that would be…anyone? Take a guess? Why, yes, Mikey -聴 that’s right! Not durable! So you’d end up taking a hike, then have to have your boots re-soled. Vibram soles come in various lug designs and hardness quotients, but you’re just not going to find one that would do you much good.
So my advice is: practice your balance, and learn to deal with it. Or, pack some alternative footwear. A pair of Nike Air Hydrous water sandals ($60), for instance, could be useful when crossing streams or wet spots. They’re made with a neoprene upper, and have a sole that’s designed to grip on wet and slick surface. But we’re not talking about “sticking” to wet surfaces, simply giving you a little better traction than a regular boot sole.
One other alternative is to pack along a slip-on set of spikes that runners sometimes use during the winter. Charlet Moser makes one such set, called the Spike Plus ($35). They’re a soft, slip-on overboot that has six carbon steel spikes built into the sole. Very light -聴 they fold up and go into a pocket 聴- but they may give you the confidence you need to cross wet log bridges.
I hear that’s a good hike. Have fun, and pack your raingear!