This is such a cool lens!, I have been itchin to get one for along time!, but I have heard of so many people getting bad copies out there.
I think that is because people with proper working gear don't usually shout from the rooftops that their lens works like it was expected to. I have this lens. Works flawlessly on my 5DII and 7D without any micro focus adjusting.
I'd go into a store though and try a copy to make sure THAT LENS is within the tolerances of YOUR CAMERA.