AlexK--Great article! Let me add my two cents!
I think that the PR'ing step and the previewing step help us to predict better as we read.
Something you might want to try is to ImageStream on the question "What is an image which will make everything in this book (or lecture) come together and make good sense to me?" BEFORE the PR'ing step, but after the purpose.
Just a short ImageStream with one or two images. Remember what the image(s) was/were as you PR and activate the rest of the book. It works on fiction and non-fiction.
That alone will triple your comprehension of a book and increase your speed.
For more info, check out www.winwenger.com/predict.htm