Objectify is a nice framework, but after reading the examples in README made me feel like I am required to take extra iterations: create new responder files, write more codes for each Responder class, etc. This approach is little tedious.

I personally think that writing reusable libraries using Decorator/Presenter patterns or Modules with ActiveSupport::Concern is simple approach.

Avdi's slides: https://speakerdeck.com/u/avdi/p/making-little-classes-out-o...

I highly recommend Objects on Rails book: http://objectsonrails.com/