Here we are almost 5 years later and I have some updates to my opinion.
My father in law passed and I took in his .410 until my nephew got his PAL. I hunted a few times with it and couldn't hit very much. I went back to the 12 when I was serious about harvesting. That is until I got a hankering for a nice 20 SXS. Now I take that instead of the 12.
My buddy still hunts with his dad's .410, but with recent ammo prices and availability, he is looking at a 20 as well, planning on retiring the .410. We spent over a year trying to find more ammo for his .410 while burning up the ammo my father in law left behind. I finally found him a box of 3" last month, $50!!! I've been buying 25rd boxes of 20 for between $12 and $18 and much easier to find. At those prices, I actually have about 2 years supply socked away in case I encounter another shortage. As I burn up a box now, I replace it and am in no hurry, so I am not stuck paying inflated prices like .410 ammo is right now.