I have these (I bought them using a 10%-off coupon, before the price jumped by $10), and I like them very much. They make a VERY stable incline/decline bench, either vertical or horizontal (unlike just using the regular flat risers,which are sometimes a bit wiggly, especially as you increase the slant). It's so stable, I can easily do decline crunches, which always felt a bit unstable with just the risers. The angle is also great for lunging onto (hits the glute area more than usual).
They can be used for cardio, but I think it's a very specific type of cardio that is designed for the slanted bench: simple moves, moves that push into/off of the bench, lots of 'travel' moves from one corner to the other, moves that don't have over-the-tops and that stick to the back of the bench. They come with 3 workouts, and the cardio one features Rob Glick teaching, with basic choreo like this that is definitely NOT what he usually does.
I'd love to see some more advanced workouts for this piece of equipment as well. If Cathe doesn't make them (the type of cardio used might not be what she's into right now), we can at least still use them for incline work in her weight workouts.;-)