I have not had a problem with autofocus on my mk111's . I did the recall anyway and the result seems to be the best autofocus I have had. I have been shooting canon sice the beginnings of the autofocus revolution. Mind you in one camera the morror box and shutter were replaced in the other just the mirrorbox. I shoot sports so this was a tough bit of testing. Indoor basketball hs gym lighting and baseball. Very happy and nothing wrong with getting a new shutter. David