I did an Instructor Renewal with David a few years back and found it was the best renewal I had ever done. He flew me hard but taught me soooo much more. The class room stuff we went through was tough but rewarding.
In the end I spent the whole day with him and came away feeling more confident than ever before about my Instructing.
If you want to be taught by someone who not only teaches you to become an Instructor but actually makes you a more knowledgable and skillfull pilot, then David is the one. I only wish I had done my initial with him.
As said before above, even my renewal was harder than my IR and 320 rating.
But he was out to make a better instructor out of me, not to fail me. And I walked away feeling confident.