When I first saw a Spetton speargun with a hinged power band attachment a couple of years back I dismissed it thinking it was just a marketing gimmick. Spearguns work fine set up conventionally with a band slot, and the inline attachment of euro guns with the screw in bands already being at the upper limit of what's really necessary. I stumbled on these pictures today and thought the design looked elegant. As is usual with these things all that glitters is not gold and there probably are disadvantages with this kind of setup that are not immediately apparent. Still it's a refreshing approach that I thought you would enjoy taking a look at.
Pretty aside, what would be the advantages in the first place of this setup? What could be the disadvantages? One of the first things that are apparent is that you're losing about 5" of band stretch (counting all the way around).
Nice solution for the grip and overall craftsmanship BTW. I like how the top bar is shaped to hold the shaft snugly.