what about these wheels?
http://www.enkei.com/kojin.shtml
They use MAT technology just like RPF1's i'd imagine they'd be somewhere in the same ball park in terms of weight. They look pretty good imo and I think would look great on the 5. Though some may disagree.
If I ever upgrade rims I'm likely going with Enkei's too. They're light, of good quality, and look good at a decent pricepoint. The style in your link would be easy to clean thats for sure.