Opinion On New or Used if I am going to change it...

[dayusmc]

So I need some opinions. I want to buy a Rolex Sub Date or SD 4000. But I want to change it some. I want the Red Second hand, Red "Overprint" of the word Submariner / Sea-Dweller and I want a Matte Black Bezel insert (either have the original one taken out and PVD it Matte Black or Put a different one in) I would have an AD do the work on it. Will this void the warranty? If it does void the warranty, would I be better off buying a used watch or still get a new one?
I have no idea where to send the face to have the Red overprint done, the bezel insert shouldn't be hard I would send that to my normal PVD coater and the Red second hand shouldn't be to hard to get.

Any thoughts?