Guns.com posted that Smith & Wesson is now putting Pro series trigger in all of M&P line due to many consumer complaints. A lot of shooters were going with APEX Tactical trigger for years and now S&W finally got the clue.
This has been going on since beginning of the year.
Link: http://www.guns.com/2015/04/13/trigger-revamp-on-smith-wesson-mp-pistols/
From: Guns.com