Pros and Cons of Platter Mass

Peripheral Rings and Puck Weights are a common used method, and when used are adding mass, where the Peripheral Ring has the added effect to increase inertia.
Each of these ancillaries when in use, add weight to the Platter and increase on the load being applied to the Spindle and Interfaces.  
I am not aware of any TT Producers putting forward disclaimers that advise against the use of such ancillaries. These ancillaries are commonly accepted as methods to be used to Clamp a LP to a Platter.

To date I have not seen any reports that suggest a detrimental outcome to a Bearing Assembly has occurred as a result of these ancillaries being used.  There may be others that know a different outcome.
   

Never understood the idea of using a hard thrust pad. Any mechanical engineer is taught that one surface of a plain bearing should be hard and the other sacrificial surface should be soft. Hardened steel shaft running in soft bronze bearings or a very common usage is in engine bearings, a bearing shell with layers of material that can be scratched with a finger nail that runs against a steel or cast iron crank pin. As long as there is a film of oil between the surfaces than no wear will occur.
Wear should always take place in the softer sacrificial material.
A time proven design for a turntable thrust bearing is a steel ball at the bottom of the spindle and a Delrin thrust pad. I have used it in my rebuilds and the Delrin seems to hold up very well with no wear on the steel ball.
My lubrication of choice is a light hydraulic oil, usually AW-32. I don't use engine oil, it has tons of additives, most not useful in a TT spindle at all. Any of the oils that have particles added and being touted as some kind of "super lube" have no place in a TT as well.
I don't understand the folks that think they will gain something by using some kind of magic oil, this stuff has been understood for well over a century and is proven. Most commercial TT oils are either a light hydraulic oil or very similar. Most general lubricants that you purchase in a hardware store are again just hydraulic oil.
Turntable manufactures don't have a tribologist on staff to formulate oil, they will look at the engineering specs on the oils available and choose one, mostly it's just hydraulic oil. This isn't rocket science.
BillWojo

The point made about Sacrificial Surfaces are important and within the Bearing Housing there are designs in place to address this.
The Spindle is usually designed to be the part that has the Hardest Surface and in a good design will usually be produced with a Case Hardened Surface.  
Bush Materials are selected that are produced to have lessened surface hardness than the Spindle.
A vintage TT that has not had a life of function with a Spindle / Bush Interface where a Hydrodynamic condition is present is at risk of having produced a wear to the Bush Material. When the Bush is produced from a Metal, the risk also becomes that abrasives may be in the Bearing Housing and having an unwanted impact on the important parts and interface surfaces. The Wear can impact on other important areas of function, especially increasing the likelihood that an eccentric rotation will develop.

A Spindle does not usually interface directly with a Thrust Pad, there is a intermediary part used that is Sacrificial, in many cases this part is a Metal Ball, that can be found to be a interference fit into the base of the Spindle or in other cases a fully exposed ball that is a standalone part.
These Balls have been witnessed scored on the surface as a result of being in an environment that is abrasive. 

The modern designs for the sacrificial parts used at the interfaces are more commonly moving away from the use of Metal and are leaning towards the use of Thermoplastics as a Bush and Thrust Pad, and the Metal Ball is more commonly seen removed from a design and exchanged for a different material that has formed the ball.

In relation to vintage TT's with long periods of use behind them where a bearing housing is using Metal Sacrificial Parts, it is difficult to condone that a application of a new lubrication only is the required treatment to produce a environment for the Spindle to function without impediment.

There are many grades of Thermoplastics with different properties for the resilience to wear.
POM and PEEK are two examples and the PEEK is common choice to be used when a Platter is going to be above a certain weight.
It does not have a property that would wear a correctly selected interface ball or will it cause damage to the Spindle.
There are more modern Thermoplastics that can be selected with properties that are further suited to the use within a bearing housing.     
 

@lewm , you need to add motor torque to that list.

I think as everything in life there has  be a balance and it depends on what type of drive is being used along with it's performance. The best direct drive motors do not require as much mass as the best belt drives.
Mass does not protect you from rumble. It might lower the frequency a little but you are also adding more thrust to the bearing, increasing noise and wear. 

How much mass is required? Whatever it takes to get the best performance and no more.

What confuses me the most is how a topic sat dormant and was revived 19 years later. I had to check to see if the OP was still with us and certainly glad he is. 
My TTW table’s plater separates into two parts for convenience, but the total weight is 70lbs. The copper weight and periphery ring add more and I’d love to know how much the the flywheel effect adds since the TTW periphery ring has brass weights.
I can say going from a less massive table to the TTW added dynamics and bandwidth to the sound. Also I feel the mass allows vibration from the stylus in the groove to sync, and the center weight and periphery ring holding the LP down essentially make the LP weigh 70lbs lowers distortion tremendously.