I have both a full size M&P (.45ACP) and a compact M&P in .357SIG. Both of these weapons have functioned flawlessly. I have put over one thousand rounds through the .45, and am coming close to that with my compact. As for issues with "fitting" in someones hand better, the weapon comes with three back-straps to accommodate just about any hand size, the weapon has a chambered round indicator, and other features that S&W can provide. My compact has a safety feature when the magazine has been dropped from the well, you cannot fire the round that is in the chamber. I have never had a problem with recoil, breakdown is super simple, and they are crackerjack accurate. The only complaint is the trigger, when I bought my F/S it took about 200-300 rounds before the trigger smoothed out, but after that period, the trigger was great.
And the last thing I will talk about is the versatility of the M&P compact in 9MM,.357SIG, and .40S&W. I don't know if Smith did this on purpose, but you can exchange barrels out for either one of the three calibers. And the magazines for .357SIG & .40 are the same, if you look on the back of the magazine it reads .357/.40. So for an extra $200-, you can have a three caliber weapon. I bought my 9MM barrel from Midway, picked up some magazines, dropped the barrel in, and in less than ten minutes, my M&P .357SIG was a 9MM. And with a magazine extender from X-Grip, you can tote 18+1. I set the gun up in 9MM, put in the small back-strap, and my girlfriend carries it (she was much more comfortable & accurate with the 9MM). Even with .357SIG/.40S&W, you can respectively carry 15+1. Here is a link that compares both S&W's and Springfield's respective weapons head to head-->
Genitron.com: Comparing 2 Guns|M&P Compact|XD Sub Compact|
I would find a place you can rent weapons, fire both, and ultimately make your own choice. I am obviously pro M&P, and for good reason, I have had nothing but an experience of excellence with both my weapons. And don't get me wrong, Springfield Armory makes darn fine weapons (I also have a Springfield 1911 Champion 4", and it is a tack driver as well). I hope this has helped you come closer to making a solid decision for yourself. Happy Thanksgiving!