You can replicate out of RDS without any problems. Shoot, you can run a master in EC2 and a replica-only in RDS.
I do this presently because I have some custom stuff I do for MySQL which needs it's own EC2 instance because RDS doesn't support it.
I do this presently because I have some custom stuff I do for MySQL which needs it's own EC2 instance because RDS doesn't support it.
My gripes with the performance issues still stand though. I have queries that take 30-40 seconds on RDS that complete in milliseconds on an EC2 instance which is much smaller.