[malisper]

I've previously administrated a cluster Postgres instances with a total of about 1PB of data. My recommendation is that you should use RDS unless you have a reason not to.

RDS takes care of tons of administrative tasks such as backups, replication, failover, and database upgrades. Yes you can setup backups yourself, but the on going maintenance is going to be a pain. You need to deal with what happens when a backup fails, have a playbook for restoring from backup, cleanup your old backups, etc. These are tasks that are extremely dangerous if you get something wrong and they are completely taking care of for you by RDS.