I hunted for several years with my 870 and I found that I preferred shooting Winchester sabots with a rifled choke. I got much better groups this way, out to about 50 yards. Later on I discovered that the only thing keeping me from getting good groups at longer ranges was the bead sight. After I bought a new interchangeable deer barrel with rifle sights on it the sabots and choke tube worked great out to 100 yards....you wont get tight groups like you can with a rifle but you can easily hit a pie-plate sized target with practice. And the Winchester 1 oz. sabot is extremely deadly, by the way, reducing the need for pinpoint accuracy. So, I'd say definately go with the rifled choke tube/sabot combo...and if you are expecting to have to take shots beyond 50 yards you should strongly consider getting a deer replacement barrell with rifle sights (under $100, I believe).
Good luck!
SC in LR