I really like the look of this ^^ thing. Especially with the quick release and measured strap. Though I've really become fond of the feel of rings.
I guess I'm a ring snob..
I'm not entirely sold on the necessity of being able to put your feet in the straps. It seems to me that using your hands on the rings is close enough to an ab wheel rollout until you can actually get the rollout.
I don't mean to come across as too much of a purist, I also use Metolius rock rings quite frequently.