Do you guys expect to see any performance increase running WoW on a 4870 vs 4870x2 with CrossFire? As I understand it, WoW does not take advantage of multiple GPU systems and actually tends to run slower with anything but a single card. Is that your experience as well?

I just bought a GTX 280 and was a bit disappointed in the lack of marked increase. I can run at 1920x1200, 16xQ AA, 16x AF, and SS Transparency AA at 60FPS indoors, but anywhere there are a lot of trees, the SSAA and high AA really kill the framerate. I am also in the WotLK Beta and the framerates in the Expansion run remarkably lower than in BC. I'm hoping they're going to tune it, but as it stands now, I can't play WoW in WotLK with SSAA enabled no matter how much I reduce the drawing level in areas like forests. I was really hoping performance was high enough on such an old engine that it could run a single instance of WoW at maximum settings. I'm thinking about buying a 4870 and trying it out as well to see what kind of frame rate I get with it at max settings. I haven't played WoW with an ATI card before and none of the recent benchmarks on any of the new cards include WoW. Have any of you tested WoW with a GTX 280 vs 4870 at high resolution and maxed out settings?