Michael,
I find that if I set a clear purpose before photoreading, then do a quick (5 min) SuperRead and Dip before setting the book down for a sleep cycle, the next day I can come back, restate my purpose (sometimes it has shifted slightly) and then do another SuperRead/Dip session in which I MindMap the key points as I read, what I come away with is a fairly comprehensive understanding of the author's overall concept/arguments.
However, I think like you, I struggle with gaining any real detail... anecdotes, facts, etc. don't seem to "jump out" while SuperReading...
and I still feel that unless I have dipped into a section, I don't have access to the information.
Amor