Are linear tracking arms better than pivoted arms?

Samujohn, all what you listen - each and everything including the reel-to-reel (invented by AEG) - was developed or its design and research which led to development was requested by military.
Hobby audio was there before WW2 - already alive and kick'in in the roaring twenties.
And yes, - I know the Tact very well and know how tempting it is. But this is not high-fidelity in the sense of the idea or phrase. It is one thing to adapt to room interaction (or better: to try to adapt to it...) but it is a different beast to alter the emitted sound to suit ideas or ideals.
It is a suitable way - no question about that - but it is not high fidelity and it is not an idea I would ever follow.

Dertonarm raises the basic question: What are we trying to accomplish with all this gear and hardware? I am 65, but when I was 17, I worked in a small, sort of "feeder" studio, some miles from Nashville. We normally used 15ips stereo tape
and recorded both music and radio ads. Our monitors were Altec A7's. I have never had a home system as convincing as our master tapes. A times we received 30ips mono ads for Coca Cola which were dubs from Atlanta. Jesus! The dynamics would make you jump! Would that I could do that at home today.
Home reproduction of prerecorded media is an entirely different situation. Digital is great, but CD's are pitiful. (I plan to throw all mine way soon.) I have little interest in listening to a studio mix on my headphones, except to analyze something. I have a modest size room and budget. I have performed some of the music that I listen to. In reproduction in my home, like most of us, I want to simulate some of the excitement of the original performance. Quad speakers,for example, or LS3/5's have a million obvious shortcomings, but manage to do more to convey the "spirt" of the performance that many full range speakers. I will try to formulate; I try to simulate, not replicate. Deliberate distortion is not bad, it is just a tool like any other. Generally I prefer subtractive distortion to additive, but not always. I enjoy my system, but others with bigger rooms and budgets do better. It's a big hobby. It's about the enjoyment of music -and friends.

I get the impression that Samujohn speaks for many of us in his last sentence :"...It's about the enjoyment of music -and friends."

I've always wondered how far can we take our technology and for me straight tracking arms were always an expression of that. I've always been a fan of the idea of them, and often more disappointed by them as a result. It is why I run a pivot arm (BTW the Triplanar has such hard bearings in it that they got investigated by the Department of Homeland Security because they use more of them than Boeing...), but regard it as a temporary measure until I see what I want in a straight tracker.

OTOH I've also wondered if there might be a way to solve the problem the other way 'round- by building a cutter head system that cuts radially rather than straight, although in looking at my cutting lathe, seems like it might be quite an undertaking...

03-17-10: Dertonarm
Darkmoebius, sorry to say in this context, that Syntax is right. While I do have respect for the brands you listed, the only "field" where the "better" succeeded for several millenia was ( and today it is beginning to change even here....) military/warfare.
In all other aspects related with demand and supply it was always the cheaper - or more easy to access or operate.

I should have qualified my comment within the framework of high-end audio, where we've gone from 15wpc triode integrated console amplifiers and speakers to 4-box actively filtered preamplifiers and 6-8 ft full range speakers in the last 60 yrs.

Darkmoebius - and high-end went back all the way to the 1920/30ies and today you have 18W SE-Amplifiers (Lamm, WAVAC etc.) and super expensive full-range drivers and speakers which usually do outperform a Linkwitz-filtered 4 way speaker with a cross-over so complex that what the amplifier actually sees, is not a coil or a "load" but a black hole.....
Same with tonearms (hurray - we are back !!) - there are 30 and 40 year old designs which still can teach most "modern" designs a few things and do.