The increased weight of the western population is a good reason for a F-20 class. Big people need big boats
I would do well to loose 10kg's myself, but I would still weight in at a decent 85kg's at 1.78meters height.

I also think the T's should be included, as there are quite many of them around. Many can be bought cheap in various conditions, and re-fitted to a Formula-20 competitive state if a young team without money wanted to race on a fast and proven platform.