XM Directory and XM Directory Lite at universities

I've read through a discussion from a couple years ago about XM Directory full vs lite, and I wanted to bring the topic up again. I recently changed jobs from an institution where we used the full XM Directory to an institution that (I believe) uses XM Directory Lite. Documentation about Lite is still pretty sparse.
To me it seems that neither of these options is well suited to the needs of a university. On the one hand, for surveys that are being sent from a university office or department to our students or employees, I would like to be using a central directory like XM Directory full, so that we can keep contact information up-to-date, unduplicated, and can monitor the frequency of contact with an eye towards survey fatiugue. On the other hand, for surveys done as part of faculty research or student projects, I don't necessarily want everyone to have access to all our constituents' contact info and don't want to put into our central directory all the invitees from every single project conducted by our faculty, students, and social research center. I really want a hybrid of XM Directory for administrative users plus Contacts for research users.
Has anyone come up with a good solution at their institution?