Almarg,
First, a correction if I may: playing with zero A/S will not cause a cantilever to deflect toward the outer edge of the record. Think about it. Groove friction pulls a cantilever along the line of its own axis (subject to minor variances in zenith alignment at any given point). Deflection of the cantilever could only occur if the tonearm resisted the inward pull of the groove. An arm with good bearings and zero A/S applied furnishes almost no resistance to the force vector created by the groove-cantilever interaction. Result: no deflection.
OTOH, playing with excessive A/S may indeed cause a deflection of the cantilever, but toward the INNER grooves, not the outer. This occurs because A/S causes the tonearm to RESIST the natural tendency of the stylus to spiral inward. The outward bias is applied to the ARM, not the cantilever. Imagine holding your stylus snug between two fingertips of your left hand whilst pulling outward on the tonearm with your right... for hundreds or thousands of hours. That's what A/S devices do, they push/pull outward on the tonearm. With the cantilever locked in the groove (your left hand) while the tonearm (your right hand) is constantly pulling outward, the cantilever is permanently pressured against its elastic suspension. That suspension may eventually take a "set", like the hole in my pillow when I wake up in the morning. That set would result in an inward-pointing cantilever.
As to sonics, I've posted many times as to why I believe zero A/S sounds best with many cartridges. Two clues:
1. re-read the paragraph immediately above, which describes what an A/S device actually does (permanently pressuriing the cantilever against the elastic suspension inside the cartridge).
2. consider that sonic penalties of excessive A/S are virtually identical to the sonic penalties of excessive VTF... diminished HFs, dimished speed, diminished air, diminished micro-dynamics, less life and zip, more weight or flab.
When the cantilver is most free to move in response to the slightest groove transient it will respond most quickly and accurately. Pre-loading the cantilever against the suspension, whether vertically with excessive VTF or laterally with excessive A/S, diminishes the cantilever's freedom to respond as quickly and completely as it might. Result: sonic dullness.
I've played with every level of A/S on my TriPlanar, from too much to the very least the doohickey is capable of to none at all. With my (mostly ZYX) cartridges, playing with none at all is the clear winner. About the only exception is some brand new cartridges, which may need a touch of A/S for best tracking until their suspensions loosen up a bit. Since my A/S device was removed long ago (with further benefits, since it's a resonance trap), I just boost VTF up a tad when breaking in a new cartridge. Not a bad practice in any event.
Other listeners have different carts or different sonic priorities, so testing for oneself is the only way to be sure what's best in one's own system.
