So basically, this KERS is that good enough you can have a +80HP car with "only" 25Kg more?
And that's the real beauty of this system once it becomes fully mature. The car can capture energy every braking opportunity, and then discharge it exiting the same corner. And theoretically, it can do this each corner of the track. Thus, Max's grand vision achieves reality with a fully functional KERS system that augments the engine acceleration every time, and thus conserves energy. Fuel savings should be realized. Maybe that's why the regulations have been changed so that cars cannot refuel during the race. That way, just by mandating a smaller fuel cell, it would force the teams towards better fuel mileage.
Of course, it's all theory right now, and the KERS system, especially the storage devices have to be able to withstand such a brutal cycle. Maybe all of a sudden, the flywheel system appears more attractive.
I agree with Metar's statement that the current batteries probably aren't capable of such a brutal cycle, and would self-destruct from the heat and other effects.
Racing should be decided on the track, not the court room.