Guess I owe RARA one eh?
He pretty much covered it all. (as he should be able to) I often suggest it's a matter of how hard you want to work the parts for the same given results. Would you put a small blower on a car and run it to the hilt or a slightly larger one that provides the same result with less effort?
Taxing the stock system to 98% may be equal to the larger rotor at perhaps 93%. Often with a nice complete package you net the same results at only 85% effort. Effort being a somewhat generic term here.
I didn't read how much larger the rotors are so it's hard to place a value on the cost to performance gains. But remember you're only talking half that for the torque numbers and maybe marginal swept area numbers for say 3/4" of dia.
