Pros and Cons of Platter Mass

I hope this doesn't qualify as a freak argument, but I believe the ideal turntable platter would be close to no platter at all (the low mass concept taken to an extreme). The platter serves only two purposes, first it provides a place for the disc to sit and second to impart the motion of the motor to the disc. Neither of these functions requires high mass. The functions that Jameswei attributes to the platter should actually be performed by the motor. To the best of my knowledge only two turntables have been designed along these principles - one by Ed Meitner and another out of England by Real Sound. I've heard neither of these turntables so I no idea about the quality of the implementation. I suspect the reason that there are so few turntables designed with minimal platters is the lack of suitable motors. Motors designed from the ground up to properly perform what a turntable motor is supposed to do and not rely upon the platter to correct for its failings.
Notwithstanding the above, I have an RPM turntable with a relatively high mass platter.

Albertporter makes solid sense and as a practical matter a high mass platter is the way to go. On the impractical side, it's interesting to note that Andy Payor's Rockport turntable uses a direct drive motor that is capable of speed accuracy in the microsecond range. The motor utilizes extensive microprocessor controlled speed correction and is reputed to cost $15,000. Payor mates it with a high mass platter.