Actually Crossfire problems used to look pretty problematic in pen 'n paper but they can be sorted out if you digg a little lower, even before the release of Catalyst 12.X driver.
There is a tool available called RadeonPro which can be used as an advanced alternative of Catalyst Control Center and it's available for long time. With this tool one can easily create custom profiles for different games where all the advnaced settings like Anti-Aliasing, AF, Tripple Buffering (for OpenGL), Midmap quality, Tesselation performance and most importantly Crossfire settings can be easily altered.
Like all the people with multi-GPU setup, I have faced problem with Crysis 2 when it was released. But it has been observed that if BIOSHOCK or Fear 2 Crossfire profile is applied with Crysis 2, it runs far smoother. I have used that trick with large amount of success until AMD released an Application Profile for the game.
Now with the 12.X drivers that can be done from inside the Control Center itself. The only problem, a CF setup with mid range cards like 6850 or 6870 might face is Micro-shuttering and it is true.
But the thing is if you're looking at a youtube Video of Game Playing just to discover it, you can notice it with little concentration but while playing the games with all your concentration, it is pretty hard to notice.
