My new M&P does the "slide slams forward on insertion of magazine" trick. So does my Glock 22. It's only a bad thing if you are disgracefully sloppy with reloading, leaving your finger on the trigger, not keeping your weapon pointed downrange at all times. In a firefight, the slide releasing itself upon magazine insertion might conceivably be kind of convenient. Thus far, I'm liking the trigger pull better than the Glock's, and I'm not experiencing the accuracy issues you are claiming.