Hey Flashman,
your original post was very well written and clear on what you are looking for. So, all you need to do is follow through with your expectation and go find it. Since you will be in Koh Tao, and also visiting Phuket for a liveaboard trip, why not take a day out and go meet the Course Directors, and visit a few the training facilities?
Just like trainers in any other field, not every instructor trainers are the same. All of the Course Directors have to go through the same training path, and teach by the same standards. However, you may find that one will have the training style that fit your needs more than others. Face to face meetings will give you the opportunity to make a well informed decision of which IDC program can get you to your goal. Because at the end of the day, a good Course Director will most likely make time for you after your course, both as a mentor & colleague. Because, real success in the instructor development course should be measured base on how long and how far you will go after the dive training, not just passing an exam.
Just my 2 bahts to help...
What an evenhanded response from one of Phuket's top Course Directors! Bravo!
(And no, Thien was not my CD.)