Does *exactly* what I need!

Multiple accounts (CARDDAV), color coding, activity tracking, tagging—and it backs itself up and restores seamlessly! My Mac OS X Server has had a couple of contact database issues that resulted in loss of data, but Busy Contacts allowed me to rebuild/restore with far less hassle than previous server rebuilds that involved exporting VCards and re-importing. You’ll find you will migrate away from groups and to Busy Contacts’ tagging approach, but that makes better intuitive sense to me anyway.

Their customer support via email is excellent (and not much needed)—I am hugely impressed and grateful for the thought that went into this app.

GVRPguy about BusyContacts