I tried using a Burris Fastfire 3 on my Browning Buckmark for Steel Challenge and didn't like the size of the screen or the way the controls worked. I sent it back and got a C-More RTS2, which has a bigger screen for much easier dot pickup and much better brightness controls and the battery slides right out in a drawer. Any optic mounted on a moving slide, better be of high quality, which means more expensive.
If I can put a $390 optic on a $330 Buckmark, which doesn't even have the optic on the slide, I would certainly put it on a $700 M&P where it does.
Buying products are like buying oats: The oats that have already been through the horse are cheaper.
See photo (Excuse me putting a Buckmark in an M&P thread), but my M&P 22 is better served with the fiber optic sights I installed).