I'd be interested in how it scales with something like Halo, which (IIRC) Bungie complained was hit with an inordinate amount of D3D overhead.
I'd also be interested in its increase in vertex shader power, if any (it's supposed to be doubled, right?).
And, uh, check to see what renaming 3DM05.exe to 3DMoat.exe or something does. Wink wink, nudge nudge.
Cough.
Maybe see if 20x15 8xS is feasible? Heck, what isn't CPU limited with dual 6800Us?
If you got 6600GTs, I'd really like further exploration into why they don't outperform a single 6800GT. I suppose it's b/c more ROPs become more helpful as people crank the res and AA in order to stress the setup?
Finally, on a more practical note, I've read posts of dual-monitor systems running at half speed unless the second monitor was disabled before gaming. Is this an issue with one monitor per card?