I have come up with a dirty solution that works by triggering an AJAX action when the role is changed, then either sets the default role (user-new.php) or updates the user’s role (user-edit.php) and finally refreshes the page.
See here: https://gist.github.com/lewebsimple/50848bbc05ec8961bf907f5c50a9d0c3
We really need ACF to support this OOTB, if it’s possible for dynamic category selections it should be easy to add this to the role selection as well.
