But you wouldn't be doing it in those 30 hours. The advantage of the mirror/log shipping method is that you get the large copy done well in advance (weeks even) of the migration window.

If you have SANs, and the new and old servers are on the same SAN, you can do (maybe) some smart snapshotting method, but that depends on the SAN and the software you have for it. If they're separate servers with separate storage, you're going to have to copy.

You can take a backup to multiple files (striping the backup), then copy them one by one. Add compression and that should get the file sizes down.