Balancing.........

Why would you have to balance "as a unit"? Shouldn't the flywheel, pressure plate and disc all rotate independently?
The pressure plate rotates with the driveshaft? The flywheel rotates with the transmission inputs shaft? and is the disc afixed to anything or does it just do it's own thing until pressure is applied from the pressure plate onto the disc thus pressing it into the flywheel?
Echo Leader......
Echo , you may "think" but the statement above tells me you don`t before you type.

STUDY UP!
If it rotated independently it would never move the car..... The disk is attached to the input shaft. The correct way to balance is to "zero" balance all components, so that fitment at one point is not necessary, or so spares or replacements can be balanced indepently.