There are others out there - as an open source project, we don't know of everywhere AtoM is being installed and used! Some others we know of aren't publicly available, or at least not yet... in other cases, we've seen users posting in the forum, but have not seen their sites. There are also several other institutions with whom we are currently discussing migration projects, or for whom we've recently completed one but the site is not public yet. Hopefully some other users on the list might reply to you as well!
Unfortunately, I don't think that any of the example sites I included above are using Record Groups as levels, and not all of them are universities or colleges, but I hope this helps a bit!