Definitely^ I forgot about that.
Especially with the poor drivers AMD offers for cards like 4870X2,5970,in some games you get a better performance with CF disabled;as a result;you get a much better performance with 6950
Not sure thats the drivers fault. When GTA4 came out, both AMD and Nvidia both had that issue. AMD actually went into their drivers and disabled CF when it detected GTA4 running. Yes the scaling is often not as good as Nvidia's, but life is better if you don't have to worry about it.
I'm not sure either but as I've read in the forums,dual cards like 5970(including mine) have problems such as high 2D clocks in idle mode also there is no way to disable CF with drivers higher than 10.10 which is bad because some games still perform better with CF disabled.