Its an RTS, frame rate plays a comparatively small role in the UX, UI latency is far more significant here. I've seen you seen you around the PA forums, you know how much of an issue the UI latency is for the game, and why I'm so worried about Coherent based games.
And as i said, GTA was actually a friend, i'm at 1GB, although i am using 1.5GB worth of resources with no significant performance issues. Interestingly, I had more significant frame-drop issues on my 4GB 290 (3GB usage) than I have with my 1GB 6850 (1.5GB), and I can't pinpoint why its stuttering.