The problem is - do we know what the problem is with the current clutch?
I could imagine a couple of issues which might cause an otherwise sound clutch to slip:
Poor friction material on driven plate
Surfaces of flywheel / clutch pressure plate glazed
Oil / coolant contamination
Insufficient clamping force from pressure plate
Actuating mechanism not releasing fully
and so on..
Replacing the friction material will only correct the first in the list, and only then if the kevlar offers a higher coefficient of friction than the current material. It could well be that this material is superior only in that it will withstand a higher temperature, for example. I don't know.
If it's got to come apart anyway, I would be addressing all the possible causes while it's apart rather than adding another unknown (non-standard friction material).
Kevin