I really love NancyFx. It's such a well thought out framework. If there is some feature missing, all you have to do is hook at the proper place. It really simplified building our startup (http://designduke.com). Best part is that using a REST framework encourages you to move out most of the logic and functionality to client and it scales pretty well.
Do you have any link that compares performance of workers to EC2 instance types (for a raw idea of how much power an existing app needs) ? Also, how does deployment to IIS server and running multiple custom executables for various other tasks workout on your platform.. I mean can a worker run multiple applications ?
We haven't made any direct comparisons, but AppHarbor web workers are very fast and can handle upwards of 200 reqeusts/second for cached responses of moderate size. For non-ASP.NET workloads, we offer background workers: http://blog.appharbor.com/2012/03/08/background-workers-in-b...
