The Palladian-A step beyond

Seems to me this conversation is getting a bit strange. Someone is saying the mechanical amplitude of cantilever movements should be the same for different carts, or types of carts?

That's a bizarre notion. Maybe you're looking at the stylus end of the stick? What really counts is the generator end. That's where the cantilever delivers the goods - excites the generator and converts mechanical movement to electricity.

Compliance is a measure of springiness. Would you expect 2 cantilevers with different springiness, made of different material, and of different lengths, to vibrate/resonate and deflect the same? 

I think the reason you can get decent results with a 64S, is because the arm/cart resonant frequency with a 'normal' cu cart goes down rather than up.  If you have a stable platform you can tune the combo with compatible headshell, tonearm wrap, damping, etc. and whatever works as long as it tracks and your woofers aren't jumping out of their baskets.

If you use a low cu cart on light arm, the resonant frequency goes up and approaches or enters the audible band which results in intermodulation distortion. IMD can sound euphonic here, reinforcing the bass or midbass, although it can cause involvement many octaves above the resonant frequency.

***Why would a MM cart have any difference in stylus movement than a MC?***

I don't think you can attribute any differences there to generator type, seems more like a function of stylus profile, contact area, groove height and that sort of thing. It might be nonproductive looking at it that way.

There's another traditional line of thought as to energy transfer and motor type and it has to do with the nature of the beast.  Because the coils are moving they transfer more energy and are more subject to returning energy. This kind of makes sense. The fixed coils in a MM are gigantic in comparison and you have a small magnet or two, wiggling.

One thing is for sure, MM's are much harder to load, but they're tunable.