[Jeff Lee]

My opinion is they have no place with a TRUE race clutch setup; i.e., adjustable sindered-iron clutch disk. These are designed to have a controlled amount of slippage on launch with an immediate release of the throwout bearing from the levers by way of mechanical linkage.
A Hydraulic system MAY be good for something like a diaphragm clutch assembly which engages more like an "on/off" switch on engagement. But I haven't put a lot of thought into that...
The question should be why do you think you need a hydraulic system in a race car? Have you put your foot on a race unit that is properly designed? I think your average Civic has more resistance.