I currently run 2x Radeon HD 6950 2Gb's in crossfire. Would this be adequate for this many monitors at 1080p?
Depends on what games, settings and what you like as far as FPS.
The 6950's will be fine for most games... but the cards will have issues with the PC blockbuster titles @ the higher settings.
I speak from experience... I run Eyefinity and 2 X 6990's. For competitive gameplay (online shooters) I disable Eyefinity and run a single screen. Not only does multi-monitor reduce FPS X 3 it also induces
Honestly, I'm kinda sick of Eyefinity and want to go to a higher resolution display ex- Dell UltraSharp U3011 30" and just use a second 1080p display as a system monitor.