It depends on the type of hunting that you do. If you hunt a lot of hills, or in real thick woods, use a smoothbore, you probably wont have real far shots. If you hunt open areas, or on the edges of timber, use a sabot. Sabots do shoot better. But, when you have a fully rifled barrel, try 3 or 4 different brands of slugs.
I shoot a rifled 1100 20 ga, and it will not shoot federals or lightfields very well. I does shoot the buckhammers great. That is an awesome slug by the way. I pulled a texas heart shot on my buck this year, and had it exit. That is impressive for any slug, especially a 20 ga.
Not to mention that the factory loads proved to group 100 shots in a 3 1/2 inch area. That is teh best group I have ever heard of for that many shots.
The BRI slugs i feel are worthless. It is a pretty good design, but the worst part is the velocities of these slugs! 1350 FPS is horrible to today's standards. There just isn't enough knockdown power to them. I used them in my 20 ga for 2 years and had to take multiple shots for my kills.
By the way for you accuracy finatics, I have done a lot of research and used just about everything, and It is a fact that 20 ga.'s are a lot more accurate. I have tried every sabot available and 20's just tend to group better and shoot a lot flatter. The buckhammers were by far teh best for me, not to mention that you get a 1 ounce sabot slug in a 20 ga! That is the same amount of lead in a 12 ga foster slug! So give the light recoiling 20 ga a try and your accuracy will sure to improve.