Phil, IMO it all depends on what you want to do with the airplane, just go in circles for training, or do some serious stunting. The Ok cub seems to be balanced for low rpm's, maybe the 5x3 or 6x3 prop. When i put a smaller cut down prop on the ok's they will vibrate too much to pick up fuel. Although i did my first loops with an OK Cub b. The Golden Bee is what we use for trainer planes to learn loops , not too much else without routing an external fuel tank. To go inverted with the Golden Bee the fuel pickup has to be set up right, and in my experience is hard to get the same runs every time on inverted unless you do those moves early in the flight. For level flying we have some GB's that have been flown and crashed a "bunch" of times and fire right back up and go. I love the way both engines sound and i still fire them up from time to time, just not much power compared to an ap wasp or norvel.