I built one with the "flatter" wing option.. and built it with the right/down plans call for. It was a sporty plane as it was built. Matter of fact, built like that, it was one of the best flying planes I've ever had . Also.. somewhere in the plans/manual/addendum it tells you how to set-up the ailerons for the differential.. I did that too.. as well as the bolt-on wing.. I think all of those options/mods combined really did make it what it was. I'd vote for all these options as per plans.. and I think you'd end up with a very spirited aircraft that will fly like no other.. These are one of the best designed planes ever IMO.