Haha, that would be one expensive regatta for those of us that like to push the line. General rule is to be over 1 in every 10 starts or you aren't pushing the line hard enough.
Starts really depend on how the line is set. In college racing they purposefully keep the line super short, such that in an 18 boat fleet, 9 boats are usually forced to a second row start. 18 F18's wasn't very crowded on the Spring Fever line 2 weekends ago. Starts were still tough but not crazy. I say the more the merrier-I think race organizers will figure out how to handle 50+ boat fleets, lets just get the fleet sizes to that point!