I can see reasons for going to more discs, but I don't understand the reason for going to less.
I've heard people say that one disc will accelerate faster than two, or two faster than three, but the math, in my mind anyway, doesn't support those conclusions.
Any calculation of the time needed to accelerate something a given distance, has to include the force available and the weight of the object being accelerated. If you're accelerating a 360 pound kart, how much time difference would one disc make? If you were accelerating the clutch by itself, then one disc would be a pretty good percentage increase, but if you're trying to accelerate a 360 pound kart, I don't think that one disc could make a measurable difference whatsoever, as far as acceleration is concerned. If anything, the extra disk, because going from one disc to two is a 100% increase in the area absorbing the power, might dissipate the heat better. Better heat dissipation would most likely give you, if not better performance, at least less stress on the parts. It's certainly not going to slow you down because of the extra weight. Not that I can see anyway!