One of the Lt's on my Police Dept has done a number of guns for guys (we cannot install aftermarket parts in duty gun *but the way the policy was written then was nothing against modification as long as the trigger pull is over 4.5lbs, he is a S&W Armorer as well).
I highly recommend the S&W Armorer course -- it's free to LE at least here (not sure what the cost is for non LE/MIL) and gives a big discount to guns.
I've shot guns with every different option of APEX trigger kit out there -- they are nice - but for about 30 min if you have the right tools and the inclination, you can get a trigger that is damn near as good.
The best way is to get the APEX hard sear and cut it (or your gunsmith if your not good with precising filing and stoning) to the angle that gives you the pull and reset you want, if your looking for the best possible M&P trigger, mainly as if you start going into the factory sear beyond a few thou it cuts beyond the surface hardening and the sear will wear soon and your gun will not be safe.