If Canon had solved those issues in some brilliant or ingenious way, they'd have put it in the 5dIII. That they are just leaving it to the T4i tells me all I need to know....it would have made pros angry since its not very good.
Check-out the video test of a Sony FS 700 https://vimeo.com/40369782
the follow focus works very well. The test was done by Andrew Young, his work has received an Academy Award nomination, multiple Emmy Awards and the Grand Jury Prize at the Sundance Film Festival.
Don't confuse the Nikon D5100 auto-focus, with a Sony auto-focus. My NEX 5n, using face detection, does a good job of keeping a person in focus as they walk around a room, even at f/2.8. If Sony can do this, why not Canon