I had a pair of these years back after using sport ultra's for a few years... I had a timing step on my second step that, with the sp. ultra's, gave a squeak of a sneaker, which kept me in time. I bought the Shufflers, and the squeak went away, so I had to adapt a new timing technique that didn't incorporate the sound of a squeak. I liked them alot, but the smooth bottom felt weird, even after a year and a half.
I use the Tour Ultras now, and I'm completely happy with them. The only thing is I go through toe caps left and right.