TT2 or TT3 linear tracker from clearaudio

A TT3 has been on my turntable for more than a year now, partnering with a SoundSmith Strain Gauge cartridge expertly set up by the Audio Ark here in Edmonton. Since this arm uses gravity, not an air pump, the rail along which the cartridge travels tilts down a bit; consequently while the horizontal tracking angle is always correct, the vertical tracking angle does change slightly as the cartridge proceeds to the centre of the record. I have no idea what measurements would show, but I've never heard any resulting distortion I could identify; actually I'm delighted with what I hear and the arm and cartridge have always behaved like lambs, no trouble at all. Important to keep the rail clean, of course.

I have owned a TT2 on a Master Reference for three years and love it.  Before that was the Tangent on a Champion 2.  Clearaudio bought Southers linear arm design and their first inhouse version was the Tangent.  I removed the Tangent from the Champion to mount a TT5.  Very mixed opinion of the TT5 especially with the required pivoted mount.  Ok, excessive, I know.  Do not tell my wife!  
All the Clearaudio linear tracking arms are tedious to set up properly!  And just because a "professional" did the set up is no guarantee it is correct.  Hence my TT5 experience.  One adjustment affects ALL the others much more than a pivoted arm.  
I am a linear tracking devotee.  Air bearing, tractor sled on rails, wheeled trolly, heck; floating!  They all work.  And yes, I understand that there must be error for the system to respond.  They are just "neat" is use and see.   Yes the platter and arm must be level, parallel and clean.  Same as a properly adjusted conventional arm.