The problem with most research supporting the use of TDD is that it compares TDD with a base line of no unit testing at all, without controlling for adding unit tests either first or last but without the test-driven aspects.

There seems to be a fairly strong case for adopting unit tests in typical commercial development processes, and some interesting debate regarding whether it is more effective by various metrics to write the tests before or after the development, but there isn't much evidence that I've seen for going the extra way to a fully test-driven process.

Yes, I have used it in two projects myself and been involved in another project where I added a few features. If you are working on a straight forward CRUD web app that does not interface with other services there is some value. One project in which I was involved and 5+ interfaces with other surfaces. Maintaining all of the mocks became very expensive. At one point it was determined that maybe half of the development time became devoted to test case maintinance. Eventually it was decided to abandon unit tests and just do integration testing. Another project was more xmpp based. I started with TDD but eventual gave up because the architure was in flux. All the experimentation put a great expense in test case maintenance. I also ditched unit tests for integration testing. You have to decide how much effort you are willing to put in test maintenance. If the expense is to greate scale back to something affordable.