Might not splinter forends be a contributing factor to drop preferences? Is it coincidence that many sxs's with "modern" dimensions also sport beaver tail forends and/or raised ribs?
It isn't the same to have the front hand 2 plus inches below the sight plane versus directly under the barrels. Gun fit isn't all in the butt. Maybe "modern" dimensions get muddled with O/U dimensions?
I don't think sxs's and O/U's should have the same drop and I don't think I'm alone on this. Maybe big drop was reasonable all along for reasons other than shooting styles and clays vs. real birds.