Sorry, I missed your reply @Adam.
You are right, cPanel will reject zone creation, if it exists inside cluster. But my initial thought was not just about migration.. Wish we could migrate away from cPanel.. but we can't - too many customers want to keep it. What we want - is to use have Enhance use cPanel DNS cluster, so we could use both control panels and have them use single DNS setup/servers.
Right now for our "DNS ONLY" customers - we use one cPanel account and park all domains there.
I imagine, that for Enhance-hosted domains, we could dedicate one cPanel account - set servername, username, API token - and let Enhance do all zone management.. if you want, I can describe it in more details.