Im running a single 22 inch at 1920x1080.
With ultra settings, and supersampling i get 60 (monitor max) everywhere except lions arch, where its about 51-52 and really heavy WvW environments where it drops to the low 40s
This is with; i7 3930k @ 4.8ghz, evga gtx 670ftw, 16gb corsair dominator, force gt SSD
So yea, i have an extremely beastly system, but its still not enough to max the game in all situations even on a single monitor.
Nvidia has promised a 20-70% increase in the next driver, which is supposed to release today or tommorrow, so I feel ok about it.
All that being said during bwe3 I played on a email@example.com and a hd6870 and it was playable on medium high settings.