A $300-$400 turntable tweak

You're right Chris.
Three weeks of un-fulfillment without being able to pinpoint a reason is frustrating.
The strange phenomenon is that the 'sins of omission' are not instantly audible when one inserts the outer ring into the system?
The return of the air and 'magic' is instantly audible upon removal of the outer ring??!
Perhaps this is one of the reasons that blind testing is so difficult and unpredictable and, in my opinion, unreliable?

I would think the ring clamp is very system dependent.
I do NOT have one, and have heard others mention problems with various ring clamps, and actually finding a different brand that worked well.
Seems VPI has a big imprint on this particular item, but other brands are available, and should be investigated if you want a ring clamp, but find the VPI to be not so great.

Syntax and Rccc are probably right about some vacuum tables. They seem to be a different kettle of fish.......I've heard the Basis Debut Gold and the Continuum Caliburn which seem to suffer no ill effects?
I would really like to comprehend a scientific explanation for the audible effects?

I agree that it does seem to be 'table dependent, along with weights and clamps. There is an inter-play with the platter surface at work that can change how the vibrations in the vinyl behave. We heard this when the Galibier platter changed to the graphite TPI and the Anvil weight became undesirable on that surface. I prefer the ever so slight bit of ringing to the compression of over damping on my Gavia. These kinds of accessories seem to work best when taken into the design of the platter, rather than added later. Mileage will definitely vary. :-)

I use ring clamp on my VPI and heard my friend's Clearaudio Innovation Wood with Clearaudio ring clamp often enough. I would not say that ring clamp is universally good for all system but to say that ring clamp is universally bad is just plain idiotic. Have you tried every tables available with ring clamp already to make such announcement? When you try it in every table and find it is universally bad then may be you can talk.