Usual story - joined a startup and their production database is a single instance RDS running 11.3.

We can't upgrade or scale or even change configuration without taking the database offline. We want to move everything to an Aurora Postgres compatible cluster that can scale horizontally.

What options do we have? I've used Bucardo in the past to do one-way sync, but how is it at multi-master replication? What would you use for this task?