This is why I haven't sent back my 629-1 to S&W to fix the end-shake and recoil-unlocking. It has an unbelievable trigger in it, but I think S&W would think it's too good (dangerous), and change it out without checking with me. (I've checked it for push-off, and there isn't any, but the trigger is so light in SA that the trigger sensation is that it's pushing foward when it let's go.)
I know from experience with another gun company, that they'll do this out of an excuse of liability, even though I own the gun... And, here is an example of them doing work which wasn't requested or authorized before-hand.
I'd rather use a private gunsmith whom I can communicate with and who will communicate with me, before doing something I didn't order and may not want.