Dwarfpool works so good for me right now!
I recommend dwarfpool for everyone. Also the cgminer on their site gives me 2x more hash than arOpenCLMAX miner.
http://dwarfpool.com/maxI'm getting 450 MH/s per r9 290

What settings are you using for 450 MH/s per R9 290? i'm only getting 380 MH/s with a 1040 Core clock.
cgminer --keccak -o "stratum+tcp://erebor.dwarfpool.com:3339" -u mRL3xNCz6KVNz4S7aiUNPcTZMwdhq7pkkL -p 1
--failover-only -o "stratum+tcp://moria.dwarfpool.com:3339" -u mRL3xNCz6KVNz4S7aiUNPcTZMwdhq7pkkL -p 1
After I start the bat, I configure both gpu's to intensity 14.
To do this, push (G), then (I), then select gpu (0, 1 etc) then type 14.
On MSI Afterburner I have:
Core Clock: 1100 mhz
Memory Clock: 1500 mhz
Power limit: +20%