>>63822452
>I would just get a 20 or more round magazine for my 2011 or my M&P.
Yes, but you'll be able to get the same capacity in a shorter and narrower magazine with 5.7.
>That's what rifles are for.
I'm not saying it's a big advantage, it isn't really. But all else equal, better armor penetration is almost always a good thing, and there's no real reason to pass it up if you're not losing anything meaningful.
>My brain and my wallet says 9mm.
And that's okay, there's zero problem with assessing the available selection of handgun calibers, weighing the pros and cons, and coming to the logical conclusion that 9mm suits your needs the best. It's a good caliber.
The pejorative in this case applies to a very common breed of NPC who stubbornly insists that 9mm is effectively as good or better than all its competitors in every single way that counts, and when confronted with arguments or evidence to the contrary, plugs their fingers into their ears and goes "lalala I can't hear you" and/or engages in a shocking display of cognitive dissonance and hypocrisy. When it comes to anything where 9mm has an advantage, it's the most important thing ever, but when it comes to anything where 9mm might have a disadvantage, all calibers are equal and everyone gets a gold star.
I use 9mm myself because I think it has acceptable terminal performance and checks the necessary boxes for accuracy, reliability, etc; and more importantly, it's what my preferred factory production handgun platform is chambered in. If I could get it in .45, I would, but I can't, and the .45 handguns I'd actually use are far too expensive for me to purchase at the moment. If I legitimately believed 5.7 were terminally equal, I would get a 5.7 handgun even if it meant making some ergonomic compromises, because the advantages would be too compelling to pass up. I don't, though; my research suggests 5.7 does significantly less damage per shot than 9mm.