I currently have x2 270's and x2 280s' and x1 290. Given that you can buy a 270 for ~200 that can do 450Kh/s and is 125 watt. I was thinking that we are better off with 2 450+Kh/s for $400 than 1 280 that does 750KH/s and pulls 250 watts. Anyone have any thoughts?