So I use a pair of these on a cyclocross training wheelset, and I sue a pair of the more expensive Sram XR rotors on my road wheelset. But despite the XR's being almost twice the cost of this model, I can not tell why these are "inferior" or the "lower end" model from SRAM. These seemed great, were a little less "heavy" looking with the more open black interior portion, and SIGNIFICANTLY cheaper than the road XR version. They do the job great, look fantastic, and don't cost a ridiculous amount per rotor.
Originally, I used an adapter on my 6-bolt rotors, which appeared to be warped out of the box, with no amount of bending would eliminate completely the occasional 'ching-ching-ching' of disc brake resonance. I upgraded to this in hope of eliminating this annoying noise, but it also rubs occasionally, and also appears slightly warped at exactly the same spot as the 6-bolt rotor rubbed. The rotor is stamped with a directional arrow that somehow during production causes a slight warp on the rotor. Not horrible, but sometimes annoying. The brakes function great, but sometimes I wish I'd chosen the rim brake option to this setup.