You mean that test DPReview did trying to focus on the white eye of a white marble horse?? Then they tried to use the USB dock and stated that it took several hours to configure it?
Curiously, because the new Canon 24-70/2.8 wasn't that great on the 650D, they felt the urge to specify that "As always, though, it must be noted that focus speed and accuracy is dependent upon a number of variables, including the camera body used, subject contrast, and light levels."
My experience with the Sigma 30 f/1.4 (ART) lens exhibits the same symptons of inconsistent AF even with highly contrasting subjects. All the microadjustment won't help inconsistent AF.