Great discussion...
I've been following this thread with interest, but I don't have anything to contribute. Why doesn't PHPA commission this kind of study? You won't be able to get what you need from the NTSB database... this one takes leg work and a statistician to make sure outlyers and distractors don't scew the meat and potatoes. The data is there and some important questions could be answered. That kind of study shouldn't be too expensive to accomplish.