+1 for the 270s.  The 7950s are good performance / watt, but the 270s are even better..

They work very well with the 13.11 Beta / 13.12 drivers. Had virtually no issues setting up 2 5 card boxes.

One box has all MSI 270s, the other box has Asus 270s and all 10 cards are doing 475-480ks on SGMiner 4.0.0 in Win8.1 x64.