I've found that on my Taipan F16 with 145 - 150 kg on board I have no issues with f18's in both very light winds or heavy winds. It is the medium wind range where I need to work hardest. But then again this can be the result of the cut on my sails.
Wouter
Wouter Hijink Formula 16 NED 243 (one-off; homebuild) The Netherlands