I'm leaning in that direction myself, depending on the price. I was trying to figure out a possible cost for the upgrade kit just yesterday myself, and came up with a possible price. But, I think I will keep it to myself for the time being to see what Hobie finally decides--don't want to give them any "bad" ideas.
I may be wrong on this, but at one time I seem to recall that one of the motivating factors for the longer Mirage drive fins was to complement the new Adventure. Thus, the BigA would come with the new Mirage drive as standard. But it took longer than Hobie anticipated to find the correct material for the new longer fins, and they were not able to meet the deadline for the intro of the BigA. But, no matter, it should still be a trip and a half to plug the new Mirage drive into my Sport and watch that baby get up on a plane!