For equivalent stability (according to OR), 3 fins vs. 6: I added a little more sweep on the fins. Six-fin version uses smaller fins; it's not a totally crazy idea. It continues to be somewhere between difficult and impossible, though, to judge what appearance will be like when the fins are clear. I'm not happy with mass/stability relationship here. I actually need some nose weight to get this thing into the proper range to fly on a D16, and that is putting it around 5 oz. For a D12 I'll need considerably more nose weight; I'll probably have to do some sort of removable weight system to make that work. Or, I just go with an 18mm mount and commit to Questjets.