Mark,
What's with the 400yd requirement? I'm going to go out on a limb and say that 400 yards might not be very far in Mt on flatish ground, but in the mountains, 400yds can be an hour hike away. And, if you misjudge a hold over, it could be another long hike to get to that animal that ran 100 + yards down the wrong side of the mountain. I say a turret is beneficial whenever a precision shot is required. Whether it be at 250yds or 600 yards, depending on what you decided is a good zero for your hunting. When I look at game shot in Montana in most of the dead animal pictures, I see wide open areas with short grass. I'm sure hold over at 400 is easy when they are standing around in a field giving nice broadside shots, but that's not a reality for the places some of us hunt.
I'll ask you.. If you put two good shooters side by side, one with turrets and one holding over, which one do you think would be able to consistently be able to make more perfect shots at 400 yards?
