As Birds says that 'cushion', which is a heavier plate with more loading, is 'easier' to drive as it allows you to slip the clutch and not have to rev it more than usual to get it off the line at the lights. The brass button or full button or puk or whatever you want to call it, the plates with the cut outs, light and without too much loading require you to use more revs to get the car moving. I'm not sure if the compound on the plates differ that much, much the surface area does, cushion having more.
From a RWD stand point I can tell you that wheel spin on inclines from lights, yes. Coming away from taffic lights with little revs results in bogging down / stall (those early morning trips to Winton I remember you!), yes. If you give it hell and launch away does it hold, yes. Does it pickup quicker than the stoker (less weight) yes.
That is 210rwkw on 255 KU36/RSR's.
If getting a NISMO twin is out of the price point, then a cushion is the option, while knowing the limits of the clutch.