Honest question about cartridge vs. turntable performance.

There never was anything special about M-S DD turntables in the first place.  By and large, they are cheaply constructed. They made their bones by building enormous metal belt drives. Hence the fact they are now making Techdas, some of which have the same design flaws as did the original and still highly sought after and still very expensive M-S belt drives.  One model even looks the same as one of their earlier belt drive efforts. 

Yes lewm, no matter how hard I try I can not warm up to Techdas tables. There is just too much filigree. They are beautifully made but more complicated than they have to be and complexity buys unreliability. For that kind of money I expect a turntable to out live me. As an example look at the SOTA Cosmos for less than 1/10th the cost of an Air Force One you get all of the same features, vacuum hold down, a suspended platter (magnets instead of air), an isolating suspension and electronic motor control. Is the Tecdas 10 times better? I would bet with the same tonearm and cartridge most of us would not reliably be able to tell the difference. Is the Techdas more reliable. I doubt it. On the other hand SOTA is right close by and has a great reputation. 
If I were going to spend crazy money on a turntable right now the Dohmann Helix is the one. It accomplishes everything I expect in a turntable in the most elegant manner at the highest levels.
Chakster, in order for any turntable to be first class it has to be able to maintain speed in spite of any reasonable interference, it has to have an adequate record clamping system either reflex or vacuum, it has to be able to mount any tonearm you desire and it has to have a suspension that isolates it from anything over 2 hertz both vertically and horizontally. 
No direct drive turntable I know of meets all of these requirements.  

How much difference does a turntable really make compared to the cartridge? Will I hear a significant difference if I upgraded my turntable and kept the same cartridge? Isn’t the cartridge 90%+ of the sound from a vinyl setup?

think of this question as a ratcheting kind of thing. where the cost of precision of each area of the vinyl ’system’ comes into dominance. as you rise through levels of turntable quality until you get to about $10k-$15k range for turntable-arm-cartridge combo’s there will be different aspects of the whole picture that will be dominant.

based on current price real production products (not DIY or Vintage).......under $1000 total mostly the speed of the platter and motor noise will be the dominant limitation. the arm, cartridge can’t overcome those limitations.

in the $1000-$2500 the motors and plinth/platter get much better, then it’s the arms that are where the compromises are and what is mattering most. any decent cartridge is limited by the arm.

above $2500 now the cartridge becomes a significant difference and set-up quality now becomes huge as the gross distortions are now gone and higher performance levels are realistic to expect.

at about $5000 now the motors and platters take another jump up in quality, and then above $7000 now some really fine tonearms can jump up. tonearms will limit or enable cartridge performance.......but there are exceptions. certain cartridges are giant killers that can be considered in this system price range.

above $10k it’s a crap shoot......too many variables to single out the dominant limitation. and everyone has a different opinion. it’s all degrees of good.

you can make a strong case that above $10k mostly you are hearing the motor and the refinement of the drive system. not so much which type as execution of concept. but opinions about exactly what is right on this subject is a very polarized subject. you have to listen and decide for yourself. lots of great choices at this level or above.

on the top of the food chain.........get to $40k and now it’s the motor and platter/plinth that separate and above that all bets are off. it gets really crazy.

I will make an exaggeration to make the point. 
Which one do you think would sound better:

- a terrible turntable with a terrific cartridge
- a terrific turntable with a terrible cartridge

i think the answer is obvious ....

The answer is it depends on how terrific the cartridge- and how terrible the turntable.

The obvious answer is the question itself is terrible.