Illinois has similar laws, so I tried it both ways.
started by using rifled slugs in a 20" smoothbore. It shot OK, but I wasn't impressed.
Then I bought a rifled barrel and used sabots. The thing shoots like a rifle with more limited range. It'll hit the same hole @ 50 yds with the right ammo.
I would recommend a rifled barrel it to anyone who hunts deer with a slug-gun.
http://www.remington.com/firearms/shotguns/870exp_slug