Is Direct Drive Really Better?

I know much less about the science and engineering of this subject than most of the excellent posters in this thread, but I feel the point I made above merits further exploration. Tom (Macrojack), your response, which is essentially that problems with the CD format obscure the big payoff it delivers in speed stability, is certainly credible, but I'm not willing to let it go at that.

What are the sonic benefits people ascribe to DD and IW? Better PRaT? What else? If this were due to better speed stability alone, surely we would hear at least some of this benefit from CDs. Do we? As piano is the reference standard for hearing pitch stability, shouldn't this be obvious from CD? (Some people think it is, but not all of us.)

My layman's hypothesis is that average speed variation from the reference (33 1/3) is more significant to sonics (and more widespread) than the very tiny moment-to-moment stability issues that are being argued about in this discussion. Rega tables run fast and -- guess what? -- they have great PRaT.

And let me toss out another idea. How stable, moment-to-moment, was the cutting lathe? And how close to perfect 33 1/3 was it? These issues confer obvious and huge advantages to digtial recording and playback, certainly on paper (listen up, Miss Pickler), but in actual practice they do not seem to be as significant as one would have thought. Ditto with inner groove distortion, the crude way in which stereo is extracted from vinyl (see an earlier thread about mono cartridges), and numerous other shortcomings of the vinyl medium.

This is truly a case of getting the cart before the horse ...and arguing that it belongs there.
The real issue is what performs better in actuality and not what should sound better. If we find that we are getting better results from one approach, then theorizing about why is appropriate but speculation about which SHOULD be better is pretty useless.
The question that started this discussion asked which IS better, not which should be.

Goodness me, I never realized that intra-analog vitriol was just as rampant as the digital-analog variety! But I for one don't find the arguments particularly strong on either side. And I don't think it's even possible to do a fair listening comparison of these two drive technologies, because I doubt you could hold everything else in the system constant.

Isn't the DD-vs-belt debate really a question of which technology offers the better trade-off between speed accuracy and rumble? And while not everything can be measured, isn't it true that those two things can be? So let's see some numbers--preferably independently verified. Where's the belt-drive table that is the equal of any DD in speed accuracy, and bests DD on rumble? Where's the DD unit that can say the same in reverse? Granted, this wouldn't settle the debate--measurements never do--but it would at least give us something solid to sink our teeth into.

Screw the numbers. Trust yer ears. I don't see why at least a very close approximation of a controlled setting which would allow a one-to-one-to-one comparison of table/arm/cart combos could not be accomplished. At least enough so that one could make a case for THEIR listening preference (what counts most). Many have done so informally and anecdotally. And, to the extent they are satisfied with their choices ends the argument in their minds. Personally I’d rather sink my teeth into the music I hear than the numbers I see on a sheet of paper, but I understand you desire to have something more seemingly solid.