I just came back from a 12 day (4 days of travel with a total of 9 hunts) Canadian waterfowl hunt. I really wanted to try a gas gun (last one I had was a Remington 11-87 back in the 1990s) instead of my tried and true Benelli inertia guns. I bought a new Beretta A300 Ultima in Max5 with a 28" barrel and kick-off stock. My thoughts ...
I tested, patterned, and cleaned the gun before the trip. I fired around 250 3" shells on the trip. The gun had two failures to strike the primer. Click with no bang. Ejected shell had ZERO primer strike. I had one double feed and one failure to go completely into battery. The weather was unseasonably cold (2F morning, 6F morning, average 11-13F morning. The 2F day had strong wind with the WC hitting -27F). The gun was used in my layout blind, A-frame and snow-goose chair. Brushing in the layout and A-frame with dead prairie grass, etc yielded lots of opportunity for debris to enter the gun. It snowed, several times.
Overall I'm mixed on it. The two fellows I went with both used their Benelli SBE3s. One SBE3 had about 10,000 rounds on it (he uses it for waterfowl, dove, clays, etc). The other SBE3 was a two season gun with around 1,200 rounds on it. The newer SBE3 jammed once (don't know what happened) and had one light primer strike. That gun had been cleaned the night before so I'm guessing he over lubricated (the high temp the next day was 9F). I think the older SBE3 had one issue.
I paid $699 + tax + shipping + GB fee + FFL fee for my A300 Ultima. All in I think I was at $823. For that money its a good gun. If I had it to do over again, I would have just taken my Benellis. In fact, I took one as my backup gun and considered switching to it, but didn't. The biggest issue for me is the kick-off stock. You can feel the stock "bottom out" and then "rebound". It made quick follow up shots less intuitive.