Cliff - regarding successful large stunt planes, I think you're right on about the Sweeper.
I restored Windy's second version to flying status a few years back and when I flew it, I was amazed at the performance. I would not hesitate to compete with it. As I recall, it was around 110 ounces.
I also have the original, a I-beam version in many pieces, that will someday fly.
To get an idea of the size, here's a picture of it hanging on my kitchen wall - compare it to the Nobler!!!
Bob Z.