We use RDS (they now support Postgres) and Elasticache.
The pricing seems reasonable for the performance (I've not done benchmarks if I'm being honest), and you get to treat all your EC2 instances as expendable.
Just to clarify: I don't eschew RDS because of outage issues, I use RDS because it's much easier to set up and manage compared to doing it yourself.
To be honest, I didn't know RDS was backed by EBS but it makes little real difference to me as long as the backup procedures are rock-solid and the performance is acceptable.
The pricing seems reasonable for the performance (I've not done benchmarks if I'm being honest), and you get to treat all your EC2 instances as expendable.