Right now I am mining with 2x7970 overclocked to 1190 core and under volted.
My system is not a dedicated miner so mhash per watt is not very good due to having silly things like hard drives, a quad core cpu and other non-mining components.
I am mining around 1410 mhash at ~600 watts.
If difficulty jumps by 10x I will be losing ~$30 a month due to power usage.
No one knows when asic will ship, but perhaps this will help you decide.