Depending on how well they do it, I may even opt in to buy it in pieces!
I think I would end ultimately buying it when it's complete.
To me being able to play it fully at once (various consecutive days), as I do with all RPGs I play, would probably provide the best experience.
But I probably wouldn't be able to resist if I was an old passionate fan like some people REALLY are to this game.
Putting me into their shoes, let's say it was a LoD remake, I would most likely jump at it asap every time we got more.
SE has some people really into a corner there.