crossfire is twice as good as sli, when you add another card you use about %70-%80 of the cards instead of Sli's inferior setup when you only get about %30-%40 of the second cards being used. Crossfire also has 3 different ways that the cards take the load.
the DFI one is very good, but it will confuse first time builders. DFI is one of those boards where you do something wrong and the stability goes to 0 percent. But when you do it right it is rock solid.