With the advent of the new edition of 40k on the way, it seems pretty clear the most effective method of purchase for me: Digital.
I know some gamers have expressed their hesitation at using a digital codex or ruleset. They are concerned about handling delicate equipment, the travel, and the lack of a nice book in their hand.
I recently found that my 6ed book had fallen apart. The pages had separated from the cover. This upset me greatly, considering it was a 75 dollar book. I don't really ever want that to happen again.
With a 60 dollar tag (25 bucks lower than the book), digitally accessible from my Kindle Fire and computer, I think this is the way I will go for the new edition.