My M&P just grew an inch....
After a measly 2 months with my standard M&P I found a used Pro series with Apex trigger, warren tactical sights, 5 mags, plus bladetech holster and mag pouch for a good price. I've now got my standard M&P9 up for sale and if I get what I'm asking it'll cost me less than $200 for the upgrade (which is less than the cost of the 3 extra mags at today's prices).
I picked it up and immediately headed to the range. For comparison I shot it back to back with my standard M&P and my groups shrunk approximately in half with the Pro with the Apex trigger. I don't know what I was thinking, thinking the newer M&P had a decent trigger. While it's not terrible, it's nothing compared to a gun with an Apex in it! While I still don't shoot the pro as well as my CZ, it's not really a fair comparison since I've got at least 2-3k rounds through the CZ and maybe 50 through the Pro.
The guy included the parts he took out of the Pro series with the gun so for fun when I got home I swapped the pro sear for the regular one on my standard. To my surprise it made the trigger pull worse! It might have been slightly lighter and a bit shorter reset, but it was hard to tell because it made the trigger loud and gritty as heck! I didn't install the pro striker block though which may have reduced some of the issues as it did seem to be the point where the trigger had the most issues. Given this, it seems that adding an Apex trigger to a standard gun is probably a better expenditure than buying a stock Pro if you're a trigger snob like I'm apparently quickly becoming.
"Finding out that you have run out of toilet paper is a good example of lack of preparation, buying 10 years worth is silly"