I think I preferred Morrison's take on why the Joker acts different at different times. Johns trying to logically explain it with there being multiple Jokers and their whole goal to make a perfect Joker or something felt a little lackluster. It feels like it is relying too much on the Jokers from the classic Joker stories to sell it instead of being its own thing. Also it is hard to get worked up about a Joker being killed because it isn't like it matters in the end. Comic book deaths have lost their luster anyway, but there will always be a Joker because he is too popular to kill off, and it doesn't really matter if there are multiple of them because they all serve the same purpose. It makes characters getting upset at him being killed feel redundant. I don't know if this will be considered "canon" but I think it probably will given how much DC is promoting it and other writers, or Johns himself, will probably do more with this story in the future given how well it sold.