I can tell you that the largest sales on the 3 bladed props has been to Central and South America. And Israel has a lot of fliers doing 3 bladed props.
If you find pictures from the recent Championships held in Columbia you'll see a lot of 3 Bladed props.
The Mejzlik 20x13 is the most popular. The SDC is almost identical but very new to the market. The SDC is as well made if not better than any prop ever made for F3A. They are very stiff and very light and the finish is near perfect.
Mike