We're using it in production in service we just launched. "Performance" is a relative term. We measured performance in:

1. Minimal amount of time to setup (minutes) 2. Minimal amount of time to maintain (none) 3. Minimal amount of time to make redundant (none, see Multi-AZ support just announced)

By the time the segment of our data we're keeping in RDS exceeds the capacity of the largest instance size AWS offers ... it'll be a very good problem to have.