I think that where you take weight off of a flywheel is the most important factor. I haven't heard of anyone lightening the inside, because lightening the outside has the greatest effect(see Breaker Bar). If you took 10lbs off the center of flywheel A it would not have as great of an effect if you took 10lbs off the outer edge of flywheel B. Although both flywheels weigh the same, flywheel B has less rotational inertia, because the mass that keeps it turning in towards the inside of the flywheel and doesn't have a long enough theoretical lever to turn the crankshaft. Also, having a lightened center sort of scares me. I've heard enough horror stories of flywheels disentegrating and cutting through peoples legs.
Interesting idea about the RA gearset. That would be interesting if someone were to dyno their car before and after a flywheel install, and before and after a gearset install. The problem is most people end up doing some heavy modifing by the time the get a gearset.