shibata or microline, pls respond ONLY if you specifically have tried both.

cleeds, "Zenith" is not something I made up.  If you have a pivoted tonearm with headshell offset, and if you then alter azimuth by rotating the arm wand back near the pivot (BEFORE the headshell offset angle is introduced), then the headshell itself not only rotates in the vertical plane described by azimuth but it also changes angle in a second plane which would alter the horizontal.  That affects VTA and probably affects the contact patches between stylus tip and groove in ways not favorable, slightly.  For example, if you rotate to the right or to the outer grooves of an LP, to change azimuth in that direction, then the rear of the headshell dips downward a bit with respect to its leading edge.  That action is changing zenith.  How important this is, I would not care to say, but it's real.  From a purist point of view, it's best not to change zenith while changing azimuth.  This can only be done if you rotate the headshell about its own longitudinal axis, without changing position of the arm wand.  I didn't intend to make a big deal out of this, but it is real.
You apparently subscribe to the physical definition of perfect azimuth, making the stylus square to the groove walls above all else.  Some others do it electrically, which does not always leave the stylus tip square to the groove.  I am actually coming over to your way of thinking after years of doing it electrically (least measured crosstalk being the electrical goal).

"Azimuth on the fly".  THAT I would like to see.I say this because the only proper way to adjust azimuth is to rotate the headshell (or the end of the tonearm that is offset at an angle) around its axis.  If you rotate the whole tonearm back near the pivot, you are not only changing azimuth; you are also changing zenith (too complicated for me to explain here).  My Triplanar is guilty of that minor sin; azimuth is adjusted by rotating the arm wand back near the pivot, so when you do make an adjustment, it also affects the angle of the plane to which the cartridge should be perpendicular (zenith). So, I am the happy owner of a 10.5-inch Reed 2A, an older model that precedes the 3P.  My 2A permits azimuth adjustment by rotation of the permanently fixed offset headshell, as it should without affecting zenith, but I cannot imagine doing that while playing an LP.  Chakster, can you say how the 3P manages to permit azimuth adjustment on the fly, without all sorts of danger to the delicate parts of a cartridge?

I think mijostyn et al are saying that azimuth changes when you adjust VTA. If not, please someone correct me. Yes, I think it would change by a very little bit, but one does not have free choice in setting VTA; VTA first and foremost has to be set to achieve the desired tonal balance and also to adjust SRA (whether one likes it or not, changing VTA is the way most of us change SRA). Thus, the final choice of VTA is very restricted by these other primary goals and would be a poor way to change azimuth. (In fact, I never heard of such a thing, so maybe I misunderstand what mijostyn and larryi are saying here.) But I do see their point that azimuth is secondarily slightly affected by VTA.