Linear Tracker ...I was wondering

jag, linear tracking arms are a waste of time and money. The technology to do it correctly has not yet been developed. The problem is that the horizontal effective mass of these arms is too high creating a very low horizontal resonance point. All you have to do is watch the cantilever closely and you will see it oscillate slowly back and forth. This creates more tracking error than a good pivoted tonearm not to mention oscillating skating force. In order to do this right the tonearm has to be driven in the horizontal plane by a servo mechanism. Little switches are too inaccurate and fragile for this. You would have to have a laser reading the groove right in front of the stylus. It can be done but at this point would be very expensive. If you are concerned with tracking error get a 12" tonearm.  

Thank you for sharing your perspective  @mijostyn. 
It had crossed my mind too. 

@jagjag, don't take everything you read as Gospel. Different linear trackers have differing amounts of horizontal effective mass. Do look into the current Trans-Fi Terrminator.

So true.
Mijo forgot to add "IMHO" ..... Again......