Yeah, if you run Ubuntu, don't try running any versions other than 11.04 if you're going to be under heavy i/o. We had all kinds of CPU soft lock issues with software raid on other versions. Otherwise? 2 m2.4xlarge running mostly standard postgresql installs absolutely dominate Mecha instances.

Obviously, you need to deal with backups and that sort of thing, but, you can hire a full time person for the price difference between Heroku and EC2 as soon as you get to the top end of Heroku pricing.