This pistol.
My M&P .45 FS
Trigger is always going to have a slight grit component to it in trigger take up as the trigger transfer bar engages the striker safety plunger. It's the nature of the beast in these pistol's. It can be cleaned up by easing the plunger profile a tad and polishing the contact areas in the slide the plunger it's self and the area in which the plunger interacts with the striker.
A M&P is easy to do a trigger job on with a few good stones and understanding how it all works and interrelates.
http://www.burwellguns.com/misc/M&Ptriggerjob.pdf
In that link you will find everything within reason that can be done to a M&P trigger. There are a few other things one can do. But I won't post them.
Here are some specs concerning my trigger.
With articulating trigger loaded in unlocked position total trigger travel .397" off the trigger stop.
Point at which trigger transfer bar is at the nose of the sear ready for action .167" off the trigger stop.
Point at which trigger breaks, when the sear releases the striker .020" off the trigger stop.
Point at which there is trigger reset .205" off the trigger stop.
I would suspect and feel that these measurements can go +/- .020" either way. And yes the polymer structure and components do add there own little bit of spongy feeling to it. But that's the way it goes in the plastic pistol world.
My trigger breaks at a very good 4 lbs. And basically breaks right into the trigger stop. Over travel is all but gone.
The mim sear takes to the stones like a duck to water. One can also deck out the top of the sear and still keep a positive engagement and also work the rear of the sear keeping a positive profile helping the over all action of the trigger.
The great thing about a M&P trigger is with no over all expense. You can make it a fantastic duty/service weapon trigger. Or a great SD/HD/Range trigger. OR you can make it a bump fire monster and dump a mag as fast as you can blink a eye. It's all up to you and your skills and what you want.
The easy way out for many is Apex. <edit> But once you look at the Apex parts and your OEM Smith parts I bet face plant to the desk top of your desk will flash before the inner depths of your mind.
And then on top of the Apex parts one can tune a tad more.
The M&P trigger is a over all great design as is the rest of the pistol.