My issues is similar, with a sad twist:
I have a Master RDS instance serving the application right now and I want to move that data to a new ENCRYPTED RDS instance.
The keyword being encrypted because none of the built in replication / slave technology that RDS has available will work due to the backups / snapshots all using EBS by default.
At first, we planned to simply accept the downtime, but using MySQLDump, the export takes 4 hours and the import to the encrypted db is taking over 13 hours.
Now we need a solution which is RDS friendly that will allow us to keep the current Master RDS instance and the Encrypted RDS instance in sync, until we decide to make the Encrypted one our new primary. At which point, we'll keep the old Master around and ALSO in sync until we're sure everything is safe.
Can anyone provide information on how to get this done?