I test rode the XR-Carbon rims before buying, they feel fine to me and I'm 14 stone. They're not that light, but well suited to the stronger rider. I think the XR-1s came in for a bit of criticism due to their tendency to flex under load, I haven't witnessed that with the XR-carbons. I got them for roughly £220 (equivelent once I'd swapped them out for the rims that came with this build - Aksiums). They are an absolute steal for £200.
Dave.