I think it's different vs old eye tracking AF. Sony version is pressing a button for the AF to track the focus on the eye. Whereas Canon version, you use the eye to focus where to focus. Correct me if I'm wrong.
I personally would love to have an EOS 3 sort of EyeAF that really works. I am surely old school, but as long as my eyes are good enough, I can track my motifs by myself (I have to when I use some of my vintage cameras). But I understand that this makes the business of wedding photographers easier. They can have more free drinks and get their job properly done, because their camera takes over most of the work. It is like in the old times when you could heavily drink and drive, because your horse knew the way home.