I have a fairly new 5DM3 that I bought a few months back directly from Canon through the refurb program. The camera has been awesome. I recently bout the EF 70-200mm f/2.8L IS II, which is equally as awesome as the body and I couldn't be happier with the results the combination produces.
There is one thing I would like to run by you kind folks, especially those of you who have the same combination. When the lens is attached it feels like there is some rotational play in it. It moves left to right about .5mm or so (in each direction. There is no up and down or back and forth play, only rotational. I called Canon service and the tech tried it with the same set-up as mine while I was on the phone and told me the same thing happened. Are any of you experiencing the same thing?