Most triggers in Sig and Smith are lawyer/state induced 10# or more pulls for semi autos. I don't buy them.
I've always bought free state guns like my M&P shield 45, that came with a decent trigger, or guns with non retarded triggers like the Canik (one of the best triggers available) , Glock or Springfield Armory. All have OK triggers, even in MA.
I did put the flat face trigger and spring kit in my Shield 45, because I liked it so much, will be keeping it, and it was easy to do. Glocks I just do the 5 cent trigger job and it smooths them out decent.
To put a whole trigger job into an M&P is madness unless your 100% sure youll never sell it. People can barely give the things away, never mind add another 100 dollars on top of it.