Cogging!

The best way to demonstrate cogging is to spin the platter by hand,  apply stylus to vinyl, and notice the sound. Then engage the motor. If the sound deteriorates in clarity or shows increased high frequency content, you have demonstrated cogging. Obviously engaging the motor will improve pitch consistency.

If you can't demonstrate cogging, it may be because of bearing noise - the bearing is so noisy that it swamps cogging noise. An air bearing TT is capable of resolving even tiny amounts of cogging, which I can hear clearly with a 1.8W multiphase motor driven by an adjustable, precision supply. For the significance of this, read Phoenix above.

I prefer kegling to cogging. 

bimasta, I've never owned or even heard a FR MC201 cartridge, or any other FR cartridge, for that matter.  Does that answer your question, which I have forgotten?  (Sorry for not having come forward sooner.)

The Denon DP80 does have a 3-phase AC synchronous motor, or so I was told when mine was in for restoration.  Probably its an iron core type but built and driven to minimize cogging. Bill Thalmann thought its motor and servo control mechanism were advanced over the contemporary Technics systems. Denon published graphs to document its smooth running in their advertising literature.  (Imagine a modern company doing the same; well I guess one or two have done.)  I don't know much about the M-S DQX-1000, except based on my reading at Vintage Knob, it is an updated version of the DDX-1000, distinguished from the latter by its use of quartz-referenced speed control.