If you were to design a tone arm, what would it look like and feature?

I like the Reed arms. They meet all of my requirements. The T5 is a bit over the edge. It is very complicated for minimal return if any. But, I have not seen or listened to one so I really have to reserve comment. In the world of mechanical devices simplest is usually best. 

The Reed arm is fundamentally, a simple, captured bearing design arm.  The only complication is the moving base that maintains cantilever/stylus tangency to the groove and eliminates skating forces.  Optical sensors have been around a long time (e.g., Beogram 6000 from the 1970's) for controlling servo motors to maintain tangency.  I don't think this makes the Reed arm unduly complicated, but, it is a matter of debate whether its advantages are worth the trouble.  The big issue, to me, is the price and possible problem with fitting such a massive arm on a particular table.

An arm from the past that is interesting to me is the Air Tangent arm.  There is one very rare model that allowed for setting VTA by remote control while the arm is playing the record.  That would be the only practical way to set VTA on a record-by-record basis.  That might be fun, although I am still to lazy to do that level of fiddling around.

I have not heard some of the ultra-exotic arms that go to extraordinary measures to damp and control vibration such as the SAT arm or the Vector Superarm 9.  These are too expensive for my consideration, but, I would like to hear them anyway.

Back in the early 80s I had a Rabco I modified. I used carbon fiber for the arm wand, and set up a more sophisticated servo system, using a capacitance in parallel with the motor.


This caused the arm servo to not quite stop and also not speed up like crazy- it would track the LP and establish a speed that kept the arm more tangential. I never got around the bearing issues of the arm and track.


But some years back I found a zero-slop slide on which the arm mechanism (designed for motion control/robotics) could be mounted.

So if price were no object I would use that slide/block system with a servo similar to what I used before: probably light activated rather than using metal whisker contacts. To this I would add something that was similar to a Triplanar in that everything could be adjusted and equipped with the hardest metal bearings available (which is what the Triplanar already uses). 

@atmasphere  Thanks, Ralph...very interesting. Would you consider the servo still to be a continuing issue with such a design. Must say, the Triplanar is an arm that I very much like, it would be hard to beat it in a number of areas. Oddly, it seems to have fallen from favor these days.

^^ Triplanar seems to keep busy somehow- if anything more busy than they used to be.

Having made a number of recordings, some of which I have mastered to LP myself, IMO the Triplanar is currently the state of the art and has been for some time. But lacking that sort of reference I can easily see why someone might think otherwise.