I am not sure if there is a simple yes or no answer to this question. I would think that your project should be very, very large in order to influence the testing of your device. My personal opinion is to leave the controllers in the web project along with the views and views. However, I am a fan of translating models into a separate project. My reasons for this have less to do with easier unit testing, and instead of reusing data access (models) in other applications.