I've actually taken to manual focusing mine most of the time because in most situations I find myself in, it's easier and quicker. The quick shift on this particular lens has never really impressed me as the AF wants to take over anyway (if I'm half pressing the shutter release).
Usually, the camera gods can tell which lens I have mounted, they already know what I want to do with it, as soon as I bring the camera up to focus, they kick up a good strong wind. It can be dead calm all day. As soon as I mount a macro lens of any sort, hurricane force winds.