I'll be re-evaluating that when I get out there and have the time to experiment in decent weather. Are you using the AF Preview (white pre-focus square) option on page 3 of the purple AF menus? I find it very handy, if it can find the eye first.
Initial video reviews and experiments suggest to have that off.
Once you focus with tracking the focus boxes stay in the VF even if AF ON is not active. So you can still toggle from subject to subject.
As you say it is early days, I have only had four actual outings with the set up.