So far you reinforce what I had already guessed - essentially the 12.
My hunting is in the Great Basin and as such is flat which keeps fatigue at a minimum.
Good points on the 20s with weight.
I'll end up getting both I'm sure but will go for the 12 first.
Follow-up: 28" barrel?
Got myself set in a Ruger Red Label. Love the Rugers! Citori a close second.