I'd add Unicode and Public Folder support, as well.
We use ours mostly for HR activities. One possibility we keep looking at is migrating users, in bulk, between Exchange servers -- I can do that on a store level by picking up the database and updating via ADMofiy or LDIF, but we sometimes want to move users based on other criteria (like Directory properties). Prime example is moving back and forth between a generalized distribution of mailboxes across servers, versus putting specific departments of classes of users on different servers. When we make that kind of change, we have to migrate mailboxes individually or in smaller batches - something that could be fed logic and migrate a large number of mailboxes would be helpful.