Today I've begun to use your miner on R9 280 for Ravencoin mining. This card is with Hynix memory (it works only on 1400 Mhz). Hashrate is 3.8-4 mh/s with about 100 watts of power consumption (GPU Core 1000 Mhz, power limit - 20%). Not so bad for such a card!
Would it be more profitable to mine XMR with it?