I actually recently just built a rig that's a trio of R9 270s (non x version). I was reading that the 270x hashrate is around 475 KH/s, and the 270 can get to 475 as well.  Currently, all three of mine are hashing at a consistent 470 KH/s each, so I'm getting the same hash power out of a cheaper card!. I got three gigabyte ones from Newegg for $180/each, and it seems most of the 270x's are going for $220+. Something to think about