Wow those look really tempting now. Pretty close to a 5970 / 6990 but without the power, heat, or noise. But as was said, they're only *just* slightly more efficient for MH/$.
I'm not sure slightly is the right word here......
BFL Single 813Mh/80w = 10Mh/1w
At
BEST, a 5970 can
MAYBE to 5Mh/1w when it is underclocked / undervolted.
So if you consider
DOUBLE the Mh/w to be
slightly, then maybe I'm dumber than I have been thinking.
Ultimately what this means is, a BFL single will be profitable a lot longer when the next significant downward event happens in price or subsidy.