I'm getting ready to purchase a new Benelli. In the past I owned a SBEII and it worked great. I'm considering buying a M2 due to the fact that i never shoot 3 1/2" shells. Is there any reason to buy one over the other...i.e. better parts, stainless steel or something truly better about the gun? Do either of the guns require the purchase of a sure cycle system? I'm using this gun 99% of the time for waterfowling.