I've heard of them, in that I periodically visit the Rearz site just to see what's going on there. I've had some good experiences with Rearz cloth (reusable) diapers, but their foray into the AB/DL disposable diaper market is more recent.
Generally speaking, I'd be HIGHLY skeptical of anybody who calls their first disposable diapers "World's Most Absorbent." 5000mL??? That's like, almost twice XP Medical's tested capacity for the Dry 24/7s, and more than twice the daily urine output of somebody who gets all his/her fluids. It just strikes me as immediately disingenuous and goofy. I'd like to see diapers compete it other ways at this point. Stupid capacities that can only be reached under idyllic test conditions aren't what we need.
That's not to say they aren't good diapers, by the way. The stated benefits just aren't all that convincing.