just a little observation on my own (long departed) Rabco straight line tonearm, fitted to one AR XA turntable:
It was an inconvenient fit, which looked like a patch-up job.
I agree. Aesthetically, there is nothing visually nicer or more elegant looking than a crisp, clean conventional pivoted arm. My favorite look is still the classic SME 3009 - like a precision laboratory scale.
However, you have missed the whole point of my post.
"I've learned a benefit of linear tracking arms that I have not seen much discussed before. Paradoxically, it is related to offset angle geometry but has nothing to do with tracking error!"
Since you didn't refer to any of my topic in your post, I'm assuming you are ignoring it or didn't understand it. I never said anything about tracking error. The rest of your post dredged up a very old argument on servo controls that's been beaten to death. Servo controls CAN be made to work well, and with imperceptible error. If you've ever been on a modern commercial jetliner, then you have entrusted your life to the smooth operation of many servo control systems (and without spilling your drink)!
...to make it the province of select few princely practicioners.
Your comment could be misconstrued as a bit condescending, but I am a gentleman and will assume that you didn't mean that. I am not a person of princely means, but I CAN afford and am able to make a servo LT work well.