Dan can probably give better answers, but as an early backer I know that I was quite eager to get in before those "early bird" copies sold out. I also recognized, though, that if I'd missed them I would have been significantly more hesitant to pledge at that point (both because the price felt higher and because it was comparatively a much worse deal). That makes me think that his (accidental?) strategy of including an early bird tier and then regularly increasing its limit might be the best of both worlds.