i use 2s for smaller canadas and snows. ive shot 100s of patterns with different shells, and i think 2s is about the best. lots of bb pattens get pretty thin for small geese. A good patterning bb shell will have 65-70 hits in a 30 inch circle at 40 yards, where as a good patterning 2 should be around 110.
Youd be surprised how many guys use nothing but 2s all a round. They do just fine on big honkers. I swear they slip through late season feathers better. Just a lot less feathers pulled into the holes than bb.