I don't even remember the last time I shot a 12 gauge at a bird on the wing.
Whenever it was, there have been a few hundred upland birds and waterfowl that were cleanly dispatched since with a 20 or 28.
For a guy that can shoot, I don't think the extra payload capacity of a 12 is worth anything at normal hunting ranges. If your exclusively pass shooting with steel... I'll take a 12 but I don't hunt like that