I figure they're virtually the same for my purposes, but I plan on getting a Shield a little bit later down the line. I've handled both and both felt good in my newbie hands. This gun will be my workhorse, I plan on putting a few thousand down range this year and doing a few training classes with it, truck gun, and eventually CC. I was leaning towards the Glock, but is there any reason to go with the M&P just because they're (9c and Shield) from the same line if they don't share mags or any other parts?