Gentlemen; I can tell you that the "H" series sear in the newer M&P's, is almost an exact duplicate of the Custom Shop sear, which, in itself, is a very close duplicate of the APEX sear. Not quite, but close. And yes, it is better than the original sear. Can a person really improve the trigger on an original M&P? Oh yes, w/o a doubt. In my personal opinion, "H" series M&P's need nothing. That's just my opinion, of course, and a person can do as he wants with his property. One of the perks about M&P's is how easy they are to modify, similar to Glocks. My big gripe is that due to past history on the earlier M&P's, everyone now think's that when you buy an M&P, you MUST buy another $100+ worth of trigger parts to make it right. And that was not true even on early M&P's, although aftermarket parts could improve the trigger. On the new "H" series guns, purchase of aftermarket parts to improve the trigger is not a true statement. These new M&P's are coming from S&W w/ absolutely great triggers, as is. Take that pistol out and shoot it! It get better as the trigger parts wear in.
BtW, the backlash on the trigger pull on a Shield can be improved, if you know how. Not difficult really. Has to do with the "Shepherd's crook" sear release. It can be lightly adjusted to change the timing on sear release thereby altering the trigger pull backlash. It can also be screwed up easily, as well.
Thanx Guys. Ofc.JL