I see, you have been very unlucky
I have to agree that when there is no profile for CFX or SLI the thing is going to get screwed because you ain't getting playable framerates.
I can't say I've had the same problems as you but I have had some (especially for being an earlier CFX/SLI adopter) and still I guess I've come out with a positive balance about it, especially because when everything works it outweighs the cons.
Still, It takes a lot more money and effort to get good framerates at 2560x1600 than 1080p, I agree with you and I damn feel your pain