As for inherent accuracy, I can't imagine there being a difference. As for practical/applied accuracy, I would think the fatter forearms would win especially when shooting off of a bench.
A Hobson's Choice: full forearm for better shooting, or narrow forearm with a tasteful schnabel for easier carrying and much nicer aesthetics (IMO), yet plenty accurate for doing what a man's gotta do. Yet another reason to own both styles!
