That's a great initiative, but I can't see that this kind of metric would be helpful with anything as personal as reading. I know this is supposed to be funny, but, personally, I don't care how long a book is or how 'difficult' it is to read. So those metrics are irrelevant--for me, anyway. However, this was sufficiently interesting for me to click through to the link. What I think is really interesting, though, is that you took the time too look at reading preference analytically. Very original. I'd like to see what you come up with next :)