How important is low W & F performance anyway?

One would assume that it would increase the resistance to stylus drag, but obviously does not eliminate speed variations.

This is what I addressed in my previous post.  Why would it change the resistance to stylus drag?  Unless the brake is operating close to the stall torque where the curve is starting to flatten any changes in drag (torque) will show up as a change in speed.

@phoenixengr 

Unless the brake is operating close to the stall torque where the curve is starting to flatten any changes in drag (torque) will show up as a change in speed.

I recall reading some years ago, in one of the English hifi mags, in an article about the Garrard, the torque curve was published, and the suggestion was that the motor was pushed into operating at a point at which the torque curve was flattening off. This is where I got my understanding around the eddy brake.

@dover The torque curve is shaped like a sine wave with minimum torque at 0° and maximum torque at 90°.  With no load on the motor, the rotor and magnetic fields are aligned (0° lag);  as the load increases, the rotor will start to lag the magnetic field as it delivers torque to the load, creating an electronic torsional "spring".  If the rotor falls behind the field by more than 90°, the torque produced actually decreases as the load further increases, the "spring" breaks and the motor will stall.  At low torque levels the angle is small and the relationship is nearly linear on the slope so small changes in drag will produce an almost linear drop in speed.  You are correct that pushing the static load up the curve will eventually reach a point where small dynamic loads will produce smaller changes but for that to be really effective means you are operating close to the stall torque which I doubt is the case.  But in theory, you are correct in your understanding.  That at least is my understanding, but feel free to correct me if I'm wrong.

There is also torque ripple to consider. Pushing the motor harder usually increases this parameter as it is generally a percentage of the average torque developed. These perturbulations would be fed into the platter. Aligning all these disparate motor characteristics for best performance is a complex balancing act and there is no perfect solution     

My understanding is that on sustained piano notes 0.2% Wow & Flutter is marginally audible, and 0.1% is typically inaudible. So if reviewers are not commenting on levels much higher than this they are either not listening to the right material or not listening carefully enough.