The only advantage I can see to a shotgun would be the psychological side of it. For some reason, having a shotgun around, especially one set up for slugs, sounds more purpose driven than having a "hunting rifle" in camp.
Otherwise, there is no doubt that a 200 or 220 grain Partition would penetrate deeper than a shotgun slug of any kind. I also don't think there is any advantage to a 220 over a 200 in this situation. I have never seen anything catch a 200 myself!
