I'm getting the same stuttering issue as error8. It'll freeze and skip forward for a split second every few seconds, and it's extremely annoying.
I'm also getting framerates a lot lower than I expected... DX10, 1680x1050 maxed, I'm getting about 14/25/40 min/avg/max (ranch small). I thought I might be CPU limited, so I forced power settings to keep my CPU throttled down to 2GHz. Lo and behold, my min framerates slightly improved, which makes no sense.
edit: Just ran some tests at 1280x800. Virtually all the stuttering disappeared, so maybe I was running out of framebuffer. The game becomes more CPU limited at 1280, showing a big difference between 2 and 3 GHz (27 vs 34 FPS). I also reran 1680 with AA off, and got some stuttering, but less than at 4xAA. Framerates were decent (22/31/47).
I still don't really understand why my 1680 4xAA results were so much lower than the article's findings, especially considering that I'm GPU limited at those settings (my results with AA off are worse than theirs with AA on).