I like a humorous approach.
If it were the zombie apocalypse, there are a lot of targets, none wear helmets or body armor... If it’s Katrina and it’s sort of like the zombie apocalypse, then too I would want something like the Sig.
If I am conducting operations in West Africa against guys that in part wear body armor and helmets, I would want something different.
Police don’t face folks with body armor often, the DoD does:
If it were just the Russians (who don’t really want an armed conflict with us) or the Chinese, that would be one thing. But today, you’ll find the use of body armor in Iraq ~20% of their troops it in 2003, Iran, even with the cartels, in terrorist groups in West Africa, Hezbollah, in the Philippines, East Timor, Somalia... It’s proliferated, and it’s something that is not a rare exception. Fielding a service weapon that is BY DESIGN not really capable of dealing with that threat, is not well thought through, IMHO.
Even a backup weapon, your secondary gun, needs to be effective.
Yes, these smaller calibers do not cause the massive damage of a 45. That’s not the issue. Yes, the Sig 320 is a great gun. That’s not the issue. The issue is that these big calibers and this great gun (in the caliber they are fielding it in) are not good at dealing with the threat that is out there.