>>> "The limitation of TDD is that it blocks rapid iteration in what the program should do. When you load the entire model of the program into your head, requirements change at the speed of thought. With TDD, they change at the speed of a lot of reading and typing."

I agree 1000% percent with that. You articulated very well what I see as the single biggest drawback of TDD.

It's as if you're still working with clay, but you put metal around it every 2 seconds, so you lose the benefit of working with clay.