Nice framework for thinking about it, thanks. Totally agree. For me, the biggest benefit is that I want to be able to refactor the internals of my code and hav

Nice framework for thinking about it, thanks. Totally agree. For me, the biggest benefit is that I want to be able to refactor the internals of my code and have the tests (which map to business requirements, not implementation details) still pass. It's also because a lot of the code I work with is inherently concurrent, and in my estimation, you're getting a lot more test coverage with the detroit model because a lot of your threading cases are simply covered if you use real objects and test it black-box style.