I have an M&P 40 compact with over 11,000 rounds. When I first got it, it had the usual M&P gritty/spongy trigger. Somewhere between 500 and 1000 rounds, it smoothed out nicely, and I was quite satisfied with it. Around 6,500 rounds, I developed arthritis in my right wrist, and needed a lighter pull weight. I had an Apex DCAEK installed, which lowered the pull weight by about one pound and made it less painful to shoot. There was no increase in smoothness, however, because by then my original trigger had become really smooth. My gunsmith even commented on how smooth the original trigger was.
Around 10,000 rounds, I started to have failure-to-fire problems. A new striker did not solve the problem, so S&W took back the 40c and completely rebuilt it. They replaced everything in the fire control system -- trigger, trigger bar, sear, striker, striker block, and all springs, including the recoil spring assembly. Now that restored my 40c to perfect working order (zero failures in 1,500 rounds since), but that also meant that I got a brand-new M&P trigger system. Yes, for a second time I now had a gritty/spongy trigger in my 40c.
However, once again, the trigger smoothed out in less than 1,000 rounds, and so I'm a happy camper.
I could have the Apex kit reinstalled (S&W was kind enough to return the parts to me), but I don't need it now. A change in statins eliminated the arthritis, so I'm now OK with the factory trigger pull weight.
Bottom line is that the factory trigger will smooth out nicely around 1,000 rounds. In my opinion, an Apex is only needed if you want to lighten the trigger pull. My advice is to shoot at least 1,000 rounds, and then decide if you want to spend any more money on your M&P.
