Just had a look at the RP site and it looks like a reliable system. The PW looks great too.
I think I have my head round the PW system; attach a transmitter to the hotshoe, and the receiver to the flash and away you go - wireless TTL with FP sync, although I'm not sure how you control outputs. Then for multiple flashes you need an SU-800 to change multiple output values that are then passed through the transmitter.
The RP on the hand relies totally on having some kind of master/commander, even when you only have one flash off-camera, because it reads the IR signal being emitted from that unit and converts it into a signal that the receiver then passes through the IR port on the flash to fire it. That's two-button interface looks a bit confusing though. Bit more belt and braces approach IMO, but it obviously works.
The PW certainly looks the tidier set-up I think, although either way I'd need to get hold of an SU-800 (which i was going to get anyway for CLS).
I suppose the beauty of both system is that it effectively takes CLS and gives it massive range and reliability under any light condition.
I'm hoping that come Focus 2011 I'll be in a position to purchase a TTL radio system so will hopefully get a hands-on demo at the show.