TALlama: I don't have a system for tracking that and because I've made a lot of incremental changes it's difficult to track mentally, but I'll try to find time to skim the Beta version over the weekend and see what I notice.
Overall, I would say that most of the changes have involved tightening the basic and playbook moves, giving advice on how to use moves, and giving advice on how to MC the game.
AlHazred: I am aware of that trap and I'm determined not to fall into it! Having everything digital should help. I also plan to keep stretch goals out of the main book so that I can get the main book done and in your hands and harddrives then deal with additional material.