Magazine capacity, as well as price for magazines and aftermarket availability. I would love to get back into an m&p, but without full capacity magazines, what's the point. S&W prices 15 round mags like they are made of gold, h&k mags are even worse. Glock 19 mags are everywhere, and not pricey. It's aboit myself and my fiance having compatible handguns, and interchangeable mags, without spending money we'll never have.