Back when they came out you really had to fight to make the batteries last 5 minutes with them on because they increased rotating mass by so much.
With lipo and brushles we now have insane amounts of power, speed and duration, so that hydras have become viable to use again. They really do smooth out a cars throttle response and make bump handling so much better, especially on slippy surfaces. Schumacher used to make a visco-drive back in the day as well, which worked similarly.
__________________
|