I personally think magnet floating designs like the Clearaudio and SOTA bearing are a more elegant solution for a thrust plate. As for which one is stiffer I have no idea. As Atmasphere implies the connection between the bearing and the tonearm base have to be absolutely rigid. With either the air "float" or magnet float designs there is an element of squish. So we have a trade off between bearing noise and wear vs squish and whatever that does to the reproduction of music. I would certainly think a compressor would wear out long before any top quality bearing and I have heard a number of top quality tables with standard bearings make essentially no noise that I could ascertain under normal use so to my way of thinking air bearings of any type are filigree. Opposing magnets on the other hand if stiff enough than why not?
I do find it interesting that this discussion has boiled down to derivations in belt drive designs.
I do find it interesting that this discussion has boiled down to derivations in belt drive designs.