I'll probably just call Winchester at some point just to be completely sure what the deal is. In all likelihood, all that'll get me is a conversation with someone who just reads back what's printed on the site, again---without being able to tell me why.
Either way, and if the slug barrel is an option, I have time to decide. I'll just hunt rifle this year, and next year I can decide if I want to dish out the extra money for a muzzleloader (and maybe a scope) or turn my shotgun into an all-around.