[Twisell]

Actually there is a third option, don't back-up your iMessage to iCloud in the first place. In this configuration you need to transfer your content from device to device using a local backup if you intend to keep your messages.

You the have the same level of privacy (if not higher) than with ADP. But with the same drawback, if your recipient does backup to iCloud without ADP then messages can be intercept by apple at rest on your recipient iCloud backup.

Incidentally ADP mainly target users that didn't trusted iCloud backup for the lack of e2e encryption at rest.