I used to own a super sharp copy of the 70-200/2.8L NON-IS.
This image is typical for the type of sharpness I got with that lens wide open..
F2.8, 1/800s, 160mm
I have heard that the IS version is not as sharp. Can users with the IS version let me know if this is about what you can expect with your IS lenses? Maybe post some 100% samples too?