Has anyone tried this? What kind of gains do you get compared to a single GPU?

I'm considering adding a second video card and wondering if it's worth it. Surprisingly I haven't found much information on it specific to CloD.

Decided to try it out for myself. It turns out that Crossfire doesn't help Cliffs of Dover at all. Testing with the Black Death track I couldn't notice any different in FPS.

Disappointing, especially since Far Cry performance doubles with Crossfire! FPS went from average 30 to a constant 60 FPS. Guess it just works better with DirectX 11 games.

Anyone else having similar experience?