RE: help me pick a slug gun
They will if you find the right loads for them, just like the H&R's. Most of the guys I know shooting modern sabots get 1-2 inch groups at 100 yards with a scope once they find out what their gun likes.
Do more research on JCC and you will find he is surrounded by LOTS of controversy as well. He used to post here quite a bit I think. The only real benefit I can think of with the H&R is it has a better trigger, and it's much heavier. As far as inherent accuracy the design really isn't any better or worse than a cantilever barrel.
Paul