Shotgun slugs versus muzzle-loaders

[BriBri]

OK. I know what are the fundamental differences between the two, in terms of how they are made and how they function. However, I am wondering from a hunting perpective (e.g., effective distance, accuracy, kill effectiveness, etc.) which one should I go with. I have a nice 20 guage O/U with which I have shot slugs out to 50 yards at the range with some decent accuracy using only the bead sight. However, I am interested in getting a scope for my shotgun and trying it on deer/bear at close range (i.e. within 50 or 60 yards). I have never shot a muzzleloader, but I know their effectiveness at 50 yards, as one of my hunting buddies took his spring bear with a muzzleloader and it made quite an entrance/exit hole (dropped the bear at the barrel). I would be interested in people's thoughts on this subject.