I've talked to plenty of anglers with the new rubber soles and have worn several myself. Basically, no one will tell you the rubber soles are better than felt. Some are pretty good and on not so slick rivers and in boats they're usually fine. I have found that the Simms Vibram soles with star cleats and studs is just about as good as felt and studs. Also, the Dan Bailey boots with studs are great too.
As much as we all like felt it's going to be a thing of the past soon. It is already outlawed in New Zealand, Maryland and will be in all of Alaska Jan. 1st, 2011. It will follow around the West in a few years I'm sure.
So if you fish out of boat, since everyone will be wearing studs with their rubber soles soon, you're going to have to put down rubber matting to save the floor. The good news is since we are going to be forced away from felt, as technology improves, someone will come up with a river safe compound that is better than felt. Think of it like digital photography. It started out as weak compared to film and now has far surpassed it in resolution and ease of use.