How ironic that you should ask that question. I gave this a shot about 5 hours ago and I was asking myself why I did it, now I know.
I regular read the book without photoreading. I went through it in one rapid read 45 minutes (mighty slow). What bothers me is that my memory of it right now... just on 5 hours later is pathetic. I can barely explain the main theme of the book and yet the idea of the book seemed so simple.
Now that was a trip down memory lane. Putting a book down, and not, really knowing the significance of why the Author wrote it. 
Given my experience with direct learning. Discovering that I knew stuff that I just Photoread without activating because I was looking for 'other' information. I know the Photofocus step is significant. The real difference is that all the information is in your mind for analysis before the conscious mind starts adding its colours to it.
The significance of photoreading as I have come to understand it and experience it is; when we regular read we continuously link the information to stuff we already know, this slows us down looking for the 'ideal' connection. We also have to guess what comes next so that what follows is connected. It seems to be like a lot of switching back and forth between right brain and left-brain while regular reading. (I came across a study that agreed with this. I've been trying to locate it again.) You do left-brain reading and then switch to right brain search for memory associations and then jump back to reading again.
Regular reading would like washing a potato at the sink (reading) then walking to the kitchen table to peel it(understanding) and then getting up and getting the next potato washing that and taking it to the table and repeating the process till you're done. Compared to washing all the potatoes (photoreading) and taking them all to the kitchen table to peel them(activating).
With photoreading you skip the switching by looking at all the word in photofocus allowing your mind just to read. Then you let it incubate, during this time your mind is connecting the information to your memory. Then you activate the information by some how calling it up to your conscious mind so that it becomes part of your conscious memory.
Re-reading a book usually creates a stronger memory and better understanding the second time around. Well, in a sense, I see the activation process as the same thing. You read the book once (photoread) and when you're activating it you are re-reading it and discovering the connections your mind has already made during incubation. This, to me, also explains why a book is much easier (easier in the sense that its a lot faster) to activate after at least 20 minutes of incubation.
I am sure that one-day science and research will be able to give the correct information as to how and why photoreading works and mine may well be redundant.
Thankfully you don't need to know how an engine works in order to drive a car. There are some steps you follow to get the car moving. Turn the key, put it in gear, step on the gas and turn the wheel in the direction you want to go and away you go. Yes, there are a lot of tricks and quirks drivers discover about driving that makes driving easier and better, for them. In thinking about it, when the car was invented most of the population did stand around looking at it wanting to know how it worked and why it worked before they would try it too. 
Alex
[This message has been edited by AlexK (edited February 20, 2003).]