My experience has been more big data management and analytics. Less on the startup angle. There are a lot of hidden costs associated with maintaining your own dedicated hardware. Our projects here invested quite a bit into several internally maintained clusters, and it hasn't been perfect. There is a lot of opportunity cost wasted in having developers forced to constantly flex their sysadmin muscles. My time is best served solving problems that leverage the cloud, not tuning and maintaining it. The context switching can be very distracting.

It's actually faster for me to use EC2 whenever I have major calculations than our internal cluster. I get on demand scaling up with the fine tune control I need to micromanage when necessary.