I have used an original Benelli SBE (H&K import) for nearly 30 years duck hunting. I don't think you need 3.5 inch capacity to occasionally duck hunt so I would get the M2.

I don't know how many rounds have been through the Benelli but it was used in a commercial hunting operation and has dispatched thousands of cripples. Thousands upon thousands. I'm afraid to put a number on it because y'all would accuse me of lying.

Best shotgun ever made. And I've owned all the rest of them right along with it. The Benelli has been the one to get treated like a rented mule. Broke ice. Dropped in lake. Found in 3" of water/mud in the bottom of the boat. Given to clients countless times when their jamomatic shotgun they brought got mud or ice in it and froze the recoil spring or maybe the weather turned the WD-40 they were using to something the consistency of honey..... and it has stood the test of time. It ain't even close to being worn out.

Best auto shotgun ever made. I'll qualify that. I'd give a Browning BPS or older 870 high marks as well.