Vintage DD turntables. Are we living dangerously?

Lewm -
With the various mats the L07D stainless & Micro 180g Copper were very close on the SP10. It is possible the differences may be more to do with mass & the actual surface profile than anything else, since they are both high impedance type materials.
People forget that platter mats are mechanical devices that not only provide an interface and base for the stylus/record, but also have significant impact on altering the resonant behaviour of the platter itself.
In particular with aluminium platters, a metal mat such as copper/bronze/stainless will dampen the platter much more effectively than say acrylic or rubber. The reason is that if you combine two materials that are close in propagation speed then reflected resonances ( which end up back in the record and stylus) are minimised.
Reflected resonances - whenever a resonance or energy passes through a material junction, most passes through but a percentage will be reflected back. The closer the materials in propagation speed, the less the reflected energy.
This is why Goldmnd and others went the methacrylate way with platters to get the impedance much closer to vinyl and minimise reflections.
In summary the mats on an aluminium platter are trying to bridge the vast difference in the impedance of vinyl versus aluminium. None of them will be perfect.

Yep......

Nope.....
Doesn't add up. The Goldmund mat was about 3mm and close to the mechanical impedance of the record. Vibrations pass through relatively unimpeded and the aluminum (usually) platter would reflect them back to the record. The mat will only take you so far and is eclipsed by the Goldmund platters methacrylate + lead.

A copper or stainless mat will pass the vibrations through to the platter with less resistance, but is dissimilar from the record and is less efficient draining vibrations in the first place.

That is why lead is the material of choice under a mat that tries to match the record. Lead is much more efficient at slowing vibrations and less are reflected back. Given the thickness limitations of a mat it's somewhat of a turkey shoot.

Fleib, in the course of marketing capacitors designed to reduce self-propagated microphonics, one of my most interesting interviews was with a respected OEM of TOTL tube amps who had been winding bespoke coupling capacitors with lead foil. He maintained that owing to its superior damping property, lead sounded better than much better conductors like copper or silver.

Fleib - please explain what doesn't add up. If you read my post I referred to the Goldmund platter, not mat. There is no difference between your post and mine.

Here is an example of the vagaries of mats - my final Audio VTT1 has a 16kg aluminium platter designed to work with a 4.5kg copper mat & 1.8kg weight. My Platine Verdier has a 15kg aluminium platter. Both are solid cylinders in shape.

On the Final the original copper mat has never been bettered, yet on the Platine Verdier the copper mat sounds awful.
On the Verdier I use a Counterparts System Mat ( distributed by Sota in the 80's) that is methacrylate with an embedded layer of barium lead. This is much better on the Verdier than the Goldmund mat you refer to. Conversely the Compositions mat sounds awful on the Final.

I think we agree on the turkey shoot, but there is some science behind what we hear.