Check out Frank Glenn @ Accuracy Unlimited: http://www.glenncustom.com/ He has done several of my S&Ws plus my Python. Randy Lee has done three S&Ws for me and I think Frank's action work is better.
M&P owners have been asking for one since they were first introduced. No luck yet. At one time, Randy @ Apex Tactical talked about building one. But, he has so many projects working now, I doubt that it will happen for a few years, if ever.