I am running a website of off a small EC2 instance. The memory on the instance is maxed out, mostly due to SQL server process. I am thinking about either upgrading to a medium instance or staying with a small instance, but transfering the DB to RDS (with the new SQL server instance).
In terms of price, both options are more or less the same. In terms of scalability, going with RDS seems to be the better choice, since it will allow me to add more server on a load balacer, and feed them all off of the same RDS DB server.
On the other hand, communication between the DB and IIS machines might become an issue, and session, cache, authentication will become more complex (share machine key and the likes).
What information and data points should I consider when making this decision?