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.