I'll tell you my experience with Safari. I signed up to look thru a
bunch of Perl books. The site worked well. I started to flip thru
the chapters of the books, like I was just casually flipping
thru "books in hand". I received an email from them saying that I was getting pages "too fast" and might be a robot, and if
it happened again, I would be kicked off safari. I just unsubscribed.
I guess they are trying to prevent people from downloading the
books. I'm wondering why they just don't sell online versions
of the books, at an attractive price. ( I guess it's a rhetorical question, :-) ; copies would pop up on Russian sites within days.