"With the restore command Gmvault can recreate your gmail mailboxes in any Gmail account. All attributes such as Gmail labels are preserved and recreated. With restore, you will recover your Gmail account exactly as it was."
I would use it just for that! When I wanted to unify my email/calendar etc. under one account there didn't seem to be anyway of transporting existing gmail over. Gmail doesn't even have a way to do it if you decide to start paying them!!