Direct Drive vs. Idler Drive vs. Belt drive

Atmasphere, I never thought it was a noise issue and I have to admit it is an intellectual bias without a shred of evidence that I know of. But magnets and magnetic fields have interesting ways of interacting with each other physically as well as electrically. My theory is that it is a distortion or tracking problem. All I can say for certain is that when these tables hit the market we were all enamored with them but quickly decided there was something wrong with the way they sounded. This is not just me but but all the audio big wigs in Miami circa 1980. The drive behind these tables was that they were cheaper, easier to assemble, much lighter (less expensive to ship) and could be pumped out in large numbers which they were. Since the Japs are capable of turning out an extremely polished device and the marketing hype was good they sold in droves until the digitally mandated vinyl crash. There are some newer DD tables I find intriguing and would like to hear but given my own experience I would never buy one sight unheard. 
One other problem is that I have never seen a DD table properly suspended. A drive be it belt, DD or Idler is entirely dependent on it's plinth for isolation. Cartridges being the very sensitive devices they are will pick up any vibration transferred from the environment to the drive. This is best and most reliably done (IMHO) by having a very inert sub chassis suspended by a system with a resonant frequency around 3 Hz.
SME and Basis tables are examples of external sub chassis. The SOTA and Linn are examples of internal sub chassis. The Walker and Air Force 1 use air springs. Other types of plinths rely almost entirely on the structure they sit on down to the foundation of the house. 

Al EMT DD are good suspended.
Two my friends -
One sold Linn LP12 for EMT 948 and other one sold Sota for EMT 950.
Other my friend prefer EMT 948 over Kenwood L07d and Technics SP10mk2, but he likes Yamaha GT-2000 as much as EMT.

I think than EMT 950 is the most unic DD. It was introduced in 1976.
It weighs ~80Kg and has ultra light rubber plate and powerful coreless motor. Even some EMT and vintage TT collectors prefer EMT 950 over idler drive EMT 927 and 930.

https://en.wikipedia.org/wiki/Elektro-Mess-Technik

Mijo, blah-blah-blah.
what could be cheaper to make than a typical modern belt drive in the under $3K price range? They multiply like rabbits. THAT is why belts became dominant. You can build one in your basement. ( I have respect for some expensive belts, starting with Dohmann Helix.) And most suspended turntables are not properly suspended. Or do you still want to ignore the placement of the motor, on or off the suspension. Either way is a compromise. If you’re obsessed with suspensions, Minus K or Herzan or possibly Vibraplane are ways to go. And each of those can be used with any drive system.

@lewm

If you’re obsessed with suspensions, Minus K or Herzan or possibly Vibraplane are ways to go. And each of those can be used with any drive system.

the Herzan active type systems can only be used when the gear has zero sensed self noise. any self noise will set up a feedback loop and burn out the device, or at least compromise the benefit. which is why it can’t be used on many turntables.

for instance it works perfectly with my dd Wave Kinetics NVS as it zero self noise. but my Saskia model two idler has considerable self noise so it’s not a candidate. most belt drives and idlers are not candidates. i could use a passive air device such as a Stacore with the Saskia and may try it.

For idle drive you need a very accurate mechanical production and professional design.
For DD you need high tech engine and electronic control system.
For belt drive you can get a cheap toy car engine, build it in your garage and sell it for thousands $$$.