All excellent except I question the acs-subsite parameter that mimics my global hack. I only question it because we will want a more general way of setting the acs-subsite's page when the portal system works (for instance.)
OK ... maybe this param's OK (thinking aloud) because it is only invoked if the acs-subsite's default index page is called, and if we add an override to deliver a portal page that's no longer true and the parameter is ignored.
Sound right?
All the expiration options you're discussing sound excellent to me, and thanks for adding the show_required_p option etc etc.
4.6 is fine I guess as long as you're willing to take responsibility for testing with these features enabled and disabled when we kick out 4.6.4.
