Is the 6990 faster than the 5870 crossfire?
I don't believe it is. It is either the same or the 6990 may be 2% overall faster. I think many of your readers would really like to see this comparison.
Remember the 69xx scales a whole lot better. A pair of 6870s will give crossfire 5870s a run for it's money. And were talking a whole step further with the 6990