You’ve clearly owned some top notch tonearms (and I’m not naming names, but you gave a few away in your comments). I try to emphasize exactly what you have done in the setup section of my support pages.
One key point I make with my customers (to the question: "which arm is best?") is that the tonearm you set up the best is the best one for you.
People interact with mechanical devices in different ways, so there is no single best adjustment design for a chosen parameter (e.g. VTA, anti-skate, etc.), but rather good ones and not so good ones.
I believe your #6 implies a #6a: adjustable effective length (i.e. cartridge slots, at least for pivoting arms).
This enables the use of arc protractors (which are designed for a fixed effective length) - knowing that the stylus offset from the mounting holes is not an industry standard. IOW, using an arm with a fixed mounting hole like the SME, the arm’s effective length will differ for a Dynavector XV1s (8.0mm stylus offset from mounting holes) vs. a Lyra which is closer to 9.0mm. Of course, with a linear tracker, an adjustable pivot to spindle distance will suffice.
In general, there are arms with great adjustment features which also sound great (I’ll stay out of naming names), and I’m all for ease of adjustment (my opening sentence).
Having said that, I might end up selecting an arm for a particular customer that might have compromised setup convenience in one or more parameters, if it fits their user profile. For example, if they were mechanically adept, and were using the arm with a conical stylus, mono cartridge, I might downplay azimuth precision (much as I don’t like to give up any design sophistication).
"Optimal setting are not for one record, but for the “mean” of all your Lps IMO."
hits the nail on the head. Finicky adjustment for each record is a path to misery, and yes, I know that it’s possible to extract the best by adjusting for each record.
Thom @ Galibier Design