Apex destroys the action package and as far as the polish and cleanup, you can do it yourself. Very easy, YouTube videos from Apex step by step instructions to install, and others such as Burwell trigger job to show how to tweak your M&P to perfection!
In layman's terms, the S&W action package is like ehhh... Ok its better than before. The Apex DCAEK and Ram is like WOW! HUGE DIFFERENCE!
but like anything that's just my opinion...
S&W M&P FS 9/357/40/45, 40PRO, 40C, 22LR