The mill isn't working twice as hard. I will make an attempt at explaining the function here.
The wind turbine blades are designed for a certain TSR tip speed ratio then the stator is wound for a certain cut in voltage at start up rpm. now as the wind speed goes up the stator is still at battery voltage so it holds the blade speed down to cut in speed theoretically. Now any blade rpm above cut in is basically heat in the stator.
so with the classic what we are doing is as the wind speed increases we let blade rpm increase to keep the blades in there optimal TSR. when we do this the voltage increases with rpm so at the same amperage we where used to getting we would be getting more watts as the voltage is increased.
Furling in theory will still work and is based on total work performed by the turbine so it will still furl around the same amperage but the voltage will be higher.
An example here is say my turbine wound for 48vdc at 6mph cut in speed at say 25mph wind speed we would see maybe 15 amps so at 50 volts that gives us 750 watts now that same scenario but running threw the classic we would see 15 amps at say 125vdc now we get 1875 watts. these are fictional numbers but the real deal can be seen at
http://data.aprsworld.com/sites/midnite/maine/
this is live data from my turbine then under it you can click on daily data and see some graphs the voltage graph is messed up a little as the data logger only reads to 100vdc and I let the turbine run to 145-150vdc
now in a perfect world I would wind my stator for 60vdc cuttin as this would allow for the typical mppt offset voltage and also allow me to still go direct to battery with a resister in line. but we do have a classic capable of 250 volts safe operational input voltage so one could wind for say 80-95vdc and have smaller wire if they had a longer cable run.