I bought one of these. The guy that owns the company says that the waterfowl modified is the one you want. He says it is comparable to a light mod. for lead.

I measured off 25 yards at the house and fired a #2 Nitro Steel into a pattern target of a duck. Then I marked and counted each pellet in the kill zone and then the ones in the legs and feet and then the misses.
49 pellets center mass, 3 to neck and bill and 19 to wings and legs. There were 79 misses outside the taget but on the paper.

I put the Beretta Factory mod. tube in and shot the same load at the same distance.

31 pellets went center mass, 17 to wings and legs and 102 outside the target but still on the paper.

There are 153 pellets in the shell I cut open.
I'll see when duck season comes around how it really works but preliminary results are good.