Actually, that's a narrow viewpoint. Express, no matter how great the benefit may be, will always impact the stand-by waits. The point is to maintain the flow of the queue and minimize waits as much as possible. It's worked out pretty damn well for Orlando when they've opened new attractions.
SNW is not Pets or JW. This is going to be a big deal. Only allowing a handful of people access will not inflate the waits at all in comparison to normal access.