I think the Tornado class has some specific wind limits. But I agree, this opens a can of worms and I generally think it is left to the PRO to make the call. If they consistently make the wrong calls, then they are out of a job, sort of self regulating.

As for safety, at the Canadian Nats, the PRO did a great job, day one he canned it when half the fleet was no longer sailing, and the second day he didn't push us too much given the conditions (although at a national event, I would push a bit harder). Personally I would have liked to have raced once more each day, but I also understand that with cats, and tipped cats, the RC's "on the water resources" get used up fast making it unsafe to run a regatta.

Now, racing in under 5knots, which rarely (RARELY) is steady... that is something I personally hate....

If anything, you need to get very specific with writing wind / condition limits into class rule. One of my favourite rules was (I think) in the Tornado class was the max number of races per day (3 or 4, can't remember), which goes a long way to ensure safety as crews wear out (not that I'm a crew or anything).

Did I mention I'm part of that Prentice and LaRoche crew JC mentions in his write up... so perhaps I'm biased against light air ;-)

Sum up; fun discusion, look at the Tornado class for an example of the right way to do it.