D80 (I can't bring myself to type 'nizzle'),
Great buy! I just picked mine up on Saturday; it's a remarkable piece of engineering and craftsmanship. All your reasoning and logic for choosing this pistol makes perfect sense to me; it's exactly the same reasons why I opted for the compact versus a Shield. I even had a Shield in-hand at one point in my search for a 40c, but my better judgement prevailed and I stayed the course. The 40c is just a little chubbier than the Shield which is what gives you a higher double stack capacity of course, but it's not so much bigger that I found it to be so much less comfortable carrying IWB. I think if anything the weight of it might be a bigger factor; a few more rounds and a fatter slide equates to a noticeable difference, albeit small, if you carry all day.
Anyhow, I think it's great just as God made it. Granted I haven't shot mine yet, but I have other M&Ps and the stock sights aren't bad. I might opt for a set of TFOs before too long, but only if I can figure out how to move the stock sights to my M&P22 as an upgrade to it. The 22s come with a all-black rear sight, makes it look a little mushy downrange to me...
Anyhow, great buy and consider what the experienced guys tell you; they're smart and have good advice. Step one is definitely securing it and using it safely. It's a pretty aggressive toy, so definitely regard it..
Be safe...
Oh, and I know a place where you can get 15rnd mags for it, brand-new. PM me if you want the contact... I know a guy with a few if them he's trying to sell, I'll see if he'll ship to wherever you live...as long as its legal of course. We're from PA, pretty loosey-goosey here compared to most places...
-sal