My comment is this is great for PHRF but doesn't make a bit of difference for OD if everyone is required to use the same sails.
PHRF-NB does not penalize for sail cloth, only sail dimensions, thus racing this sail in PHRF is an advantage becuase there is better performance with no PHRF penalty. I am sensitive to the desire to keep OD costs at a minimum. Thus, if the 0.5 oz spinnaker were allowed in OD, everyone would feel the need to carry both a 0.5 and 0.75 ounce spinnaker, increasing the cost for OD. The class rules allow a backup spinnaker if the primary spinnaker is destroyed. My backup is an older 0.75 oz class spinnaker that is well used but serviceable. For the "arms war" reason, I would not be in favor of adding the 0.5 ounce spinnaker to the OD sail inventory.... but could see a rules change similar to something proposed below.