That 90watts difference? easy that come from the generator not have a lenz effect slowing it down, that 90 watts come from you having a larger diameter generator thats 6 times as long because you have all the torque from the driver. That extra energy come from the additional larger pick up coils/ magnets an leverage.
What you said - the trade off - still apples but how you are achieving your 100watts is different, The energy already exist inside the wire waiting to be moved around as it does with commercial systems. but unlike commercial systems that slowing under load is delayed to the point it becomes a positive effect.