I ride a rev-x rear. Some thoughts:

The spacing is 130mm. I took a grinding wheel to the hollow axles and shaved it down to 120mm. They are Q/R only. If you want to use a Surrly Fixxer on the Shimano cassette, you need to file down the pawls (I can't find the link. I think it's on FGG). With the thread-on freehub one, I had some problems getting a good chainline with my cranks. I am going to use one of those track adaptors for disc wheels (like these. $35 for just the adaptor).

Anyway, YMMV. They sure look cool!