Are linear tracking arms better than pivoted arms?

Dear Pryso - as a more direct answer to your question 02-22-10 directed to me - the "stress" on the cantilever mounted in a pivot tonearm (if we leave skating-force aside for a moment and address the force vector only, which promotes the movement of the tonearm.. ) is very different from the one applied by guiding a linear tracker.
The derivation force in the linear tracker adds a force to the stylus which is about 90 degrees off - i.e. in the linear line - towards the "normal" (read: in pivot tonearm) force which does (normally...) point towards the pivot point of the tonearm.
The cartridge and its cantilever ( every cartridge - even DECCA/London and IKEDA with their "string" holding the "vertical" cantilever or arc in position) are designed to address that ("normal") force only and thats why that "linear derivation force" in a linear tracker puts indeed - no matter how careful set-up, leveled etc. - an additional stress on the cantilever/suspension system.
And it does so in a way the cartridge was not designed for to withstand for long.
A short sketch on white paper will immediately illustrate the forces and the dilemma.

Remembers me to the day from my good old times when I was asked after listening to the Goldmund Reference with the T3F Arm which Cartridge I would mount in that Arm? Goldfinger, UNIverse, Olympos or even something more expensive????
My answer was "Go for the cheapest one or to that one you hate most".
I saw the movements from that Arm and the smeared soundstage was one of the results.
But honestly, I guess, that was not the answer the other one wanted to hear :-)

Excentric records kill all theoretical advantages of passive linear trackers. Doing simple math, you can see a side force as large as up to 1.0 gramm peak applied to the cantilever when say, 200 gramm of slider+arm mass is driven by 1 mm out-of-center record. Cantilever ealisy moves more than 1 degree from centerline under such force. In perfect world of ideal records, when the arm moves accross the record with virtually no acceleration, high lateral mass is a good thing, allowing needle to follow groves while the arm stays steady due to high inertia. From my personal experience with 120 g air tracker, 1-1.5 mm eccentricity is pretty audible, not to mention lead-out groove, where cantilever bouncing becomes scary.

Well, after starting this thread and reading everything everyone has written, I have decided to give pivoted arms another shot. After numerous emails with Dertonarm, I have decided to buy a Fidelity Research FR64s tonearm. I know Raul thinks the AT is superior, but based on its low resale value, I decided against it. If for some reason I decide I don't like the FR, I am confident I can get my money back. I am looking forward to all of the parts coming in (I bought the arm, a new TNT armboard from VPI, and a NOS Orsonics headshell). It is my hope that this combo will sound better than my ET-2 in all parameters. If it does, I will gladly sell the ET-2 and be done with linear tracking arms once and for all. Since the arm is coming from Australia, the headshell from Hong Kong, and the armboard from VPI, it will be awhile before everything arrives. It should be interesting and I hope worthwhile. There must be a reason why the FR64s has a cult following and the value continues to climb.

Livemusic, Good point about lateral mass. I have lately started using a Dynavector tonearm, which is deliberately designed to present a high mass in the horizontal plane. I can only say it is a great sounding tonearm with lovely bass response. However, I think the possible negative effect of high mass in the horizontal plane is ameliorated (at least) by the pivoted design of the Dyna tonearms.