For those who want to know the tech stack. We are running on heroku(the european datacenter)[1] and amazon S3, we use RoR with some pretty nice gems(active admin, devise, ...) and Jquery for the JS. For metric we use Mixpanel and Google Analytics. For our emails we use Amazon and Mailjet. The are on the european DC because of the Safe Harbor. http://en.wikipedia.org/wiki/International_Safe_Harbor_Priva...
Is infrastructure a noteworthy portion of your spending? (10-20%+?)
Either way, cool concept, I'd definitely consider using it.