Most racing J/30 sailors don't have a decent #2... so their choice is either a #1 or #3. Those of us who do have a halfway decent #2 find it quite uesful, especially when you don't have enough crew to hold the boat down.
The problem with a #2 is you have a choice to make. With only a #1 and #3, that choice is pretty obvious.
It's probably better to use a #3 when you've got waves you have to drive around, and a #2 when there's flat water where you can point very high.
