Great summary of many of the issues with our current sensor technology, Dave.
In the past I have wondered about QE and why it shows such a complex relationship to frequency. After reading your post I actually got around to looking for an explanation and found one here:
http://learn.hamamatsu.com/articles/...fficiency.html. It was an interesting read. If only I could afford a camera with a back-thinned CCD!
Cheers,
Rick.