I've been burned to many times by 3rd party HA solutions for Postgres. I'm not touching it again until they either have an official solution or if it is someone else's problem (eg. RDS).
We also use RDS in Zalando (and it works great!). With running Patroni on Kubernetes we get several benefits over RDS which in our opinion warrant the effort. Some examples include:
* Real superuser access to the cluster
* Installing custom PostgreSQL extensions not available on RDS, PgQ (Queues in PostgreSQL), PgDecode (logical decode to Kafka/Json), PgJobs (minimalistic jobs in PostgreSQL)
* Easier migrations via S3/Streaming replication from and to AWS - RDS currently offers no way out of RDS to another PostgreSQL cluster
* Deployment model allows for more availability/flexibility with less costs - EBS + S3 allow us to run single node PostgreSQL with high uptime
* Multi node PostgreSQL can run on different node types
