I want to hear Github's side because I think I'm missing something. If based solely from this side of the story, it seems like Github certainly would be better off staying with Engine Yard as a paying customer: EY's support was good, they delivered beyond expectation and they certainly brought a certain amount of success to Github. But in the end, Github still decided to pack and leave rather than pay and stay.

There must be some compelling reason for Github to make such a weird decision. The question is what?