Here’s where I say (to Mijo) that I owned a Star Sapphire Series III with vacuum platter for about 10 years, as my one and only turntable. I sold it in the late 90s. I replaced it with a Nottingham Analog Hyperspace, another belt drive but an unsuspended one. Then came a succession of direct-drive turntables including a Technics SP10 Mk3 and a Kenwood L07D and a Lenco that I highly modified with slate plinth, massive upgraded bearing, Phoenix Engineering motor control, etc. My cumulative post-Sapphire experience revealed to me early on that the Sapphire had very poor speed stability. The decay of piano notes was frequently "sour". Bass was muffled and indistinct. And etc. Back in the 90s, I thought what I was hearing from the Star Sapphire was simply typical for vinyl reproduction. I realized the deficiencies of the Sapphire very quickly after purchasing the Hyperspace, and the issue was even more clear after I added a motor controller to the Hyperspace. All my subsequent turntables confirmed my initial post-Sapphire impressions of the Sapphire. I think a weakness of that old SOTA design, as I have noted many times, is the fact that the motor is mounted on the immobile plinth, while the platter floats on the suspension. This causes the belt to stretch when the suspension is activated, and may be the cause of the audible speed instability.
I do understand the potential value of suspending the works of a turntable, and I think the way to do it is to take an unsuspended turntable and put the whole shebang on a MinusK or Herzan platform. When you mention megabuck belt-drive turntables, you neglected to include the Doehmann Helix, which incorporates a Minus K stand into its structure. I have had some experience listening to the Helix, although I cannot afford one, and I found it to be the best sounding belt-drive I have ever heard. The Air Force turntables likely also air-suspend the entire chassis, to eliminate the stretching belt phenomenon, but I’ve never heard one. The fact remains that the SOTA Star Sapphire is not a contender. Since I do admire SOTA as a company, I would also mention that their more modern models (Cosmos, Nova, and Millenium) may have dealt with the problem I mentioned. And by the way, my Lenco is as silent as any other turntable I’ve heard, and in that system I run massive dedicated woofers in stereo from 100Hz down. We can argue all day about whose turntable is quiet and whose is not, but the point is that the 301/401 can be made to satisfy some discriminating audiophiles in that regard, your opinion notwithstanding.