Heres a question for you...would you use a butter knife to twist a wood screw or the proper screw driver? My point, why not use the proper equipment for the specific application? Rifled slugs were made for smooth bore shotguns, Sabot slugs were made for fully rifled shotguns. Yeah, you can shoot ether round in ether barrel, but why chance wrecking the gun or ruining the chance at a trophy if the gun ever failed. I've watched a buddy wrack a nice shotgun due to fouling in the rifled barrel, because he was too cheap to buy some Sabot slugs.
My 2 cents