There are a lot of good questions there.
The one thing that I can say for sure is that he was immensely inspiring. That we are all here talking about this today is proof of that, and that must be an important thing for any teacher.
Of course, he was quite difficult to understand, and came out of a tradition of paranoia and secrecy that probably helped exacerbate the problem. Certainly, if we look around at the actual transmission of ability and skills than there seems to something lacking.
It may be that he was so monomaniacally focused on his own training that everybody else just got left behind.
A mixed grade, to my mind...