I don't see how that is possible. There are tons of combinations for slider tricks. I agree with the crack smoker price comment though. They are rediculous.
I've never been on one. But people who have say the sliding surface isn't very good, and they just say the whole thing is kinda flimsy, and not very sturdy. Alot of unesesary movement. They look like a good training tool to me. But and upturned kayak will work just as good, just a little short.