In my opinion, we don't need this rule change for one design and we don't need this rule to help to be competitive in PHRF.
I own a composite main, a 1/2 oz spinnaker and an A-sail. All are used for PHRF racing. Only one, the composite main is additive to my costs of racing one design. the others are incremental costs that I decided I needed for PHRF.
Since all boats have the same inventory in one design, all have the same advantage/disadvantage in light, heavy or whatever wind conditions. If this rule is put in place it will greatly increase the cost of one design racing. I would then have to buy a 1/2 oz spinnaker for one design and another for day to day PHRF racing (I have a one design sail inventory and another for PHRF/day to day racing).
My suggestion is to leave the one design rule as is and for those of us that want to buy additional inventory for PHRF - spend the incremental money