So, back in July of last year my M&P 9mm old-style (black) striker broke. S&W sent me a new style (silver) replacement that I dropped in. See: link .
I am pleased to say that after 6 months the replacement functions perfectly and the trigger is much improved like the newest versions that you buy off the shelf today.
Woohoo! Kudus to S&W for taking care of this and continuously improving their products! I also own a 9c and will be adding a 40S&W model shortly.