No your not thick, the only relative motion will be a slight bit as pressure is first applied to the pushrod ( spinning shaft , stationary ball in the r/h adjuster) I have found ( after making a few) that the main advantage of the alloy plate is the fact it is a snug fit over the clutch centre thereby centralizing it, whereas the standard pressure plate
sits on the first plain plate in the middle & only has the spring studs to centralize it.
ps if the alloy plate is not a snug fit over the centre it is no better than the original.
Hope this makes sense.