Had the Fabarm out and shot a whole bunch of slugs. My findings:
Brenneke Rotweil - best accuracy, ~ $4/slug, extremely heavy recoil
Challenger Magnum - 2nd best accuracy, ~ $1.80/slug, moderate recoil
Federal Truball HP - 3rd accurate, ~ $1.30/slug, little recoil
Federal Tactical Low Recoil - 4th accurate, ~ $1 ($0.80 bulk)/slug, no recoil
The Brenneke (depending on penetration, shock, and take down power) would work for hunting, definately not worth target shooting. The Challenger was only slightly less accurate, but far less recoil, and proven penetration power and fun on the range. The Truball is good all around, and oddly enough the Tactical is the least money with the least accuracy by far but can be shot all day long with no pain...
The surprise of the day was Royal Long Range buck shot (12 pellets - .32 size), that kept very tidy groupings (5 inch diameter pattern at 25 yards) out of a 14" barrel... all for $0.95/shell. Little recoil... great round.