I think so: shorter is often better. I have read 6 technical books in the last 6 weeks (4 were free from the publishers, which was really nice). One of these books would have been excellent if it was shorter: the author would make a good point and then repeat the same thing one or twice in the next dozen or so pages. I think that author was not well supported by his technical editor and editors. A good 400 page book could have been edited down to an excellent 200+ page book.