Pros and Cons of Platter Mass

Jameswei is correct, his answer is absolutely in accord with my own experience, and I have owned perhaps fifteen turntables .

My current table utilizes a 70 pound platter and must be push started, even though it is air bearing. No doubt it is the quietest, most speed accurate and lowest wow and flutter of any table I have ever heard. Not too surprising, considering the laws of physics.

Can't tell ya...however, I do know the pros and cons of hitchiking!

Fatparrot, does it include a guide to the galaxy?

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.

Onhwy61. In an ideal world, your ideal zero mass platter would be great. In the real world mass is required to smooth out the energy drain from the stylus retrieving heavily modulated passages from the vinyl.

The motor you propose would have to not only turn at exactly the correct speed, it would have to recover in microseconds to any variation in drag coefficient or velocity changes. This might be possible, but for the present time, a heavy platter turned by a belt to isolate the less than perfect motor is the best we have. Much like the designers decided on for your RPM.