Sikorsky does not need to re-write the flight manual for the Carson blades.
This is something accomplished by a supplement. Carson already has an approved supplement for their blades. However, as far as I know they have not completed testing to included an amended WAT chart. That is where the problem lies. The blades DO increase performance greatly, you just can't legally use the extra payload numbers until the WAT chart is amended.
Carson has stated that they are confident that a new WAT chart would give an increase of CAT A weight of at least 1400 lbs, or in other terms a 10 deg C reduction. I.E. on the Sikorsky WAT chart on a 28 degree day you would enter the chart at 18 degrees to see what the Carson blades would give you.
Even without the supp, the increase of 10-15 kts in TAS = less fuel required = more payload.
cheers