bumping this thread, as I find myself looking into this very issue at the moment (gettijg some scratches polished out & edges/lines sharpened)...
Assuming some custom trigger tuning has been done, will S&W mess with or alter that in any way if only requested to do a complete polish?
Concern is just about the potential for them to "reset" a trigger/hammer release which may be beyond any further improvement, but barring that seems like a no-brainer.