I chose the Nacra 17 because it is the only boat on the list that is fully optimized for what the OC wants. The Viper (the next most voted boat) is not optimized for a two person 120-140kg crew, it is designed to work well either 1-up or 2-up, but that isn't what they want. I expect the Nacra 17 would be more "athletically challenging to the elite sailors of the world" that happen to add up to that weight range.