I picked up the 2007 model on sale for $180 (clearing stock for 2008). Sweet looking and feeling bindings.

In case anyone else had similar issues to Perrywarrior...here is my comment in response to the question about the "lean" on the bindings:
I have the 2007 Burton Cartel model...the 2008 model is slightly different, but as you probably know you can adjust the angle of the "lean" using the buckle on the back. When I first strapped in to these bindings, I did notice that even on the most vertical angle, they lean forward more than my previous bindings. After gettting out on the hill I didn't have any issue with it, and I find the bindings very comfortable. You want to be leaning forward in your bindings slightly rather than being straight up. If you are having pains from the back of the bindings, perhaps your boots are not compatible with the cartel bindings. You can adjust many of the straps and settings with the Cartel bindings, so maybe try tinkering with some of those adjustments to see if you can make your boot fit more comfortably.