I've got a pair, on a ride on Saturday the nipples on one of the spokes pulled out of the rim, taking part of the rim with it. And another part of the rim is fracturing at the base of another spoke. No crashes, potholes etc - just seems to have failed.
On the positive side, Planet X are great about it, they're sending another wheel.
I'd buy another pair, and they're a steal at £99.
I had to take my cassette off in order to send the old wheel back and it was a bit of a struggle as it had chewed into the freewheel a bit (Shimano Ultegra cassette).
I understand there's less of an issue if you use Dura Ace as the load is spread across the carrier.