It's really not a question of the 410 being "superior". Actually, it is more a question of the 410 being suitable for SD...and it certainly is.
For a while, I experimented with a Saiga 410. It was a fantastic gun. I felt quite well armed with it loaded with a five round mag of buck.
The only reason I sold it was the combined length of the Kalashnikov action and barrel, and the plastic stock...made for a weapon that was a little too long.
But, when I look at the new 410 loads available today, like the PDX, I wish I still had that Saiga to try them in.
Still waiting for my Flashback...I would like it now, please.