Intergral locks don't seem to be that invasive. I have a Ruger MKIII with a lock and I just filed the key away and don't use the lock. I'm more concerned with FPS problems that may be lurking out there.
No. If you want one, buy the one Springfield Armory puts on their 1911s and put it on the S&W 1911. The parts interchange. The SA lock is in the mainspring housing. I personally would not, but some people like that sort of thing.