If you centre spot the AF on the 5DII then you will get accurate AF. It is the focus points outside the center which are not good in low light and also the area the the A points cover is less than the 7D
In hindsight buying the 7D was a mistake as the IQ of the image is nowhere as good as the 7D, plus the bokeh is very poor. The 7D will get more in forcus pictures but none of them will be as good as the in focus 5DII picture
Thanks... and the fact that I almost always use Center point AF is why I never found the AF to be bad... by the way; is the 5d2 Af better than the 5Dc or are they the same (especially for Center).