One important note, for those of us who live in CA with the Handgun Roster, this is the "easiest" way to get a ported CORE/PC M&P. I got a 4.25" slide from grabagun about a week ago and put it on my 2013 M&P9 full size with a Trijicon RM06. Haven't tested it yet since my usual range just went out of business, but hoping to check out a new place this week.
Any update? Have you shot yours yet? I live in CA as well and thinking of getting the 4.25" or 5" PC slide 9mm.