Conrad, it might help you to consider the backgrounds of the people who have met Dan and been incredibly impressed by what he can do and how easily he can teach others to do it. We're talking about people with decades of experience with direct students of Morihei Ueshiba, many of them having lived a number of years in Japan.
On the other side of the argument, who ya got? Graham?
Show me someone with decades of experience and time in Japan who has met Dan and found him lacking. Give me one name, huh?
That's a good argument, but there could be other reasons why nobody has publicly come forward with a negative opinion. In the public sphere, Dan has a history of being somewhat aggressive in the face of criticism. Most people would rather not get dragged into a public conflict.
To clarify, I'm certainly not arguing that IP/IS is BS. I'm simply pointing out that I don't feel convinced based on what I've read on the Internet (absent of direct experience, admittedly) that it is the holy grail of martial arts and the missing component in 99% of the world of aikido. The rhetoric around it has been pretty hot and heavy.
That's a pretty small and personal claim to make, in my opinion. I don't think any rational human would begrudge me the right to apply the usual critical thinking skills. Once you give that up, things get cultish pretty quickly.