I put the DCAEK in my full size M&P9 and absolutely love it. I have sold many kits for Apex by simply letting other people shoot it at the range.
My compact M&P9 came from the factory with an excellent trigger, smooth and crisp. So even though I have a DCAEK kit sitting here for it, I have yet to put it in.
My gunsmith, who is the FFL guy who receives my guns or if bought locally, has always gone over them nonetheless, pretty much always finds room to improve the triggers on my guns and offers his recommendations as such.
When my 40c came in, he went over it and said: "That trigger, as delivered, is the best I've seen on any M&P so far".
Feeling there's typically some variability from gun to gun, I was delighted. This is the same guy who didn't want me to leave the shop with a BG380, that has a 14.5 pound trigger pull until he brought it down some, but for a gun that resides in my busy pockets, that amount of weight is fine with me.
I handled a lot of M&Ps before buying and overall, I felt the triggers felt pretty darn good on the whole lot of them. The feel of the trigger was the first thing that caught my attention.
The main reasons I eventually made the purchase were because of how 'right' the grip and overall balance felt, the crisp triggers and of course, the gun's reputation for reliability and accuracy.
Yes, my 40c's trigger has a little bit of creep and I can feel a little grittiness, but I think with time on the range and a lot of dry firing, it will only get better.