Well there is always question of $ if running on Phoenix would let you save $100/month it's one thing if it's 100k/month things might look a bit differently and

Well there is always question of $ if running on Phoenix would let you save $100/month it's one thing if it's 100k/month things might look a bit differently and when it is 1 mil/ month things that will change equation even more. (This is not going into areas were Ruby is not a usable option such as massive real time apps etc.)