I have seen a couple times in this thread that 5S is mentioned as the preferred SPA setup, but I can tell you as an active SPA flyer and electric flyer, I have never seen a 5S setup in SPA. Everybody is running 6S. Most guys are using that 6S with lower Kv motors to spin props more comparable with a 4s 91, but I made my propulsion target more along the lines of what the airplane was designed for. With regard to the extra weight of 6s over 5s, my Phoenix is 6lbs-4.5oz up all battery in and ready to fly. If I built another I'd probably shoot for 7lbs to handle turbulent air a little better. When choosing my setup I wanted my Phoenix to fly in the same flight envelope as our old Phoenixes did in the old days. I can assure you it is no WindS with Curare decals, and I doubt it sees 60mph even on the uplines. It may have fixed gear and be a taildragger, but it flies like a classic patternship was designed to. Jamie Strong could attest to that. At the Masters in Chattanooga he was flying a Dirty Birdy with a Nova Rossi on it and my Phoenix was faster.