"...My guess is that since Racers are such an important market they will not deviate from a totally class legal boat in any way. China does have quality control problems but looking at older Sunfish I'd say the quality varied widely from boat to boat and manufacture. Today's manufacture quality should be far above yesterdays processes. All in all racers should come out the winners.
If new Sunfish come out of the chocks with totally class-legal boats, racers would already have a head start over the older boats. That said, selecting the right older boat, and "tweaking" the bottom to limit flex could put the (many available) older boat(s) ahead. Including mine! With time, such standardization with new injection-molded hulls certainly ought to settle the question of fine-sanding the hull.