"cases where you need more fine grain control and customizing Rails can be a PITA" I'd love to see some examples where customizing Rails is a PITA and made eas

"cases where you need more fine grain control and customizing Rails can be a PITA" I'd love to see some examples where customizing Rails is a PITA and made easier by using Sinatra. Personally I have little trouble making Rails do what I want, since I can get at the underlying Rack objects when I need to do things at the HTTP protocol level.