I was very interested in the Fushion last year and opted for the Beretta 391 Urika. I realize that there are some differences with the Xtrema, but there are a few insights on the Beretta I can give you.
My Urika performed very well in the first year under tough conditions. I found it to have a very different feel from the Browning. The Browning seems a little more weight forward, and also may have a bit more drop. I have had a hard time getting my Beretta to fit just right and tend to shoot a little high with it. I have since noticed that all Beretta's seem to fit me in a similar way. My Urika never had a jam or misfire all year and has some nice features.
My only complaint, other than the fit, is the location of the safety. It is a cross-bolt with the location on the front of the trigger guard. I found it awkward to have to reach forward to hit the safety, then move my finger backward to engage the trigger. It took some getting used to, and I had the gun go off just as I was shouldering it, several times. This problem seemed to go away once I got used to the motion. The Browning safety is nice and large and sits at the rear of the trigger guard which I find to be a better design.
The Xtrema should be quite a bit heavier, I think, and will also come in a sythetic stock. The Fushion is a very light 12 gauge and only comes in wood. If you plan to hunt waterfowl, the Fushion does not have a good option for a sling. I looked into this and found that the standard Gold sling mount kits will not work on the Fushion.
Good luck.
