I have a Smith M&P 9C. I enjoy carrying it and I'm comfortable with the trigger as it is. However, I carry a Glock 22 everyday and have all kinds of time behind that gun. Im looking to upgrade the trigger on my 9C, and looking for advice from anyone who had done so already.
If you are looking for aftermarket, look up apextactical, they seem to be top dog for m&p trigger parts. If you want to stay stock, google "burwell trigger job", that is what I did to my 9c. My trigger feels much smoother, and it just cost me some time polishing stuff. The burwell job will not shorten the pull, just smooths the feel of it. If you are wanting a shorter pull, or want a lighter pull weight,I would look at Apex.
Better reset, shorter trigger stroke, lighter pull weight, no hinged trigger if replacing trigger. I will let the lawyers speak about any issues from modifying a stock trigger in a defensive gun.