I've shot the M1 Super 90 at ducks for 10 years or so, and am happy with it. It may be a victim of its own marketing, however. It hiccups every once in awhile just as every gun I've ever owned did. This is no big deal--I've dug plenty of rounds out of the carriers of various 870s, and spent way too much time trying to get an old Rem 878 auto to repeat.
Before all this lightning fast surefire claptrap, most shooters understood that a shotgun was a mechanical device that would let you down from time to time. Once Benelli started parting us from an inordinate amount of cash, someone had to come up with a rationale. I got mine because it felt good in my hands, but the $630 I paid stung a little less when it was explained that this was a genuine whiz-bang technological marvel with a new and miraculous locking system. Well guess what--the laws of physics still apply.
It's simple. If it's not working right, it should be simple to fix or to trade to someone who will fix it. There is no santa claus and there is no voodoo that makes a gun foolproof just because it wears a Benelli, Sauer, Merkel, Anschutz or Hammerli handle.
I hope your S90 gets to feeling better, perhaps by more frequent use with fresh, full power loads.