Like said before they are the two top models for waterfowling but all of the top 3.5" guns are really good to. So this is a no lose situation just buy the one that fits you best, I have owned most of the 3.5" guns out there and my opinion is that the Benelli will last the longest, The one advantage the Benelli has is that is the most proven model out there and if you start having problems you can get after market parts easier than dealing with Beretta or Browning direct, most of the SBE I parts will interchange with the SBE II other than the stocks. But I would not really expect to have problems with any of them the Maxus is having a few teething pains but they are minor, The Super X3 seams to be a great gun with no major issues, the SBE II problems seam to be from cleaning issues that can mostly be solved by adding a $13.00 Wolff spring for those that dont clean the recoil spring. and some Xtrema 2's have had issues with a roll pin wearing in the bolt causing light primer strikes but thats only after lots of use it's another cheap and quik fix.
Well thats my 2cents, Kurt