One of the friends I shoot with has the M&P shield in .45 and I've put probably 50 rounds through it without much of a problem. So recoil with .40 isn't something that I am particularly concerned about. I appreciate the input though.
This is a serious misnomer. I hope you have actually shot a 40 before, and extensively at that. While I have nothing particular against it, it is not a 45. Just because the 45 is larger doesn't mean it has more felt recoil. In fact if most people I know had to rank it, they would do 9mm < 45ACP < 40SW. I do not like the 40SW in a light subcompact gun. In a metal firearm or one with some weight okay, but even then I find I don't shoot it as well as the other two calibers.
If you don't mind me asking, what is your reason for going the 40SW route?