Re: .40 S&W vs 9mm
If you do go with the M&P full size, I would get the .40. I have an M&P40 full size, and you can buy a factory 9mm barrel and drop it right in (you will obviously need 9mm mags though). I have over 1500 .40 rounds through it, and around 300 9mm rounds, and not a single FTF, FTE, etc. I am a relatively smaller guy (5'8", 150#) and while the .40 isn't terrible (as mentioned everywhere, it does have that "snappy" recoil), the 9mm feels like a .22 after shooting the .40. If you are going practice for self-defense and shoot more than just one round per few seconds, the 9mm is FAR easier to keep/get back on target (for me, personally)