I'm perfectly happy playing at that resolution
So there isn't micro stutter for 687 CF
All I can say is I don't have any micro-stutter
As for your resolution, what I said is you're not going to see much of a gain @ that resolution
There isn't really anything that a single 6870 can't max @ 1366x768 so why spend another $150 for a second card?
If you're set at playing @1366x768 I'd take the $ and invest it somewhere else in your rig