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.
Are linear tracking arms better than pivoted arms?
My answer to this question is yes. Linear tracking arms trace the record exactly the way it was cut. Pivoted arms generally have two null points across the record and they are the only two points the geometry is correct. All other points on the record have a degree of error with pivoted arms. Linear tracking arms don't need anti-skating like pivoted arms do which is another plus for them.
Linear tracking arms take more skill to set up initially, but I feel they reward the owner with superior sound quality. I have owned and used a variety of pivoted arms over the years, but I feel that my ET-2 is superior sounding to all of them. You can set up a pivoted arm incorrectly and it will still play music. Linear tracking arms pretty much force you to have everything correct or else they will not play. Are they worth the fuss? I think so.
Linear tracking arms take more skill to set up initially, but I feel they reward the owner with superior sound quality. I have owned and used a variety of pivoted arms over the years, but I feel that my ET-2 is superior sounding to all of them. You can set up a pivoted arm incorrectly and it will still play music. Linear tracking arms pretty much force you to have everything correct or else they will not play. Are they worth the fuss? I think so.