This is one of the reasons I don't like this device, and measure speed in mine differently - basically, by first asserting test-instrument frequency-measurement accuracy using a test test CD's 1kHz tone, then adjusting tt speed until I get 1kHz output from the amps with a test LP. This still suffers from speed variations within the test LP itself (due to potential cutting lathe speed variations), and/or the tt's motor; therefore, I eventually adjust for a range from 999 to 1001Hz (sometimes readings are outside this range), and then revert back to the KAB strobe - and it appears that my speed as measured by the KAB is overall dead steady - apparently, the SDS speed controller does its job. Recently, I am relying more on the KAB for final speed adjustment than ever before, and it looks to me it's good enough.
The other reasons I don't like the Timeline are: 1) unknown mass, affecting speed in indeterminate ways when removed and replaced by one's own clamp/weight of different mass and rotational properties; 2) it takes a very long time to make a decision
I also simply use my KAB and am satisfied with the results. However, the Timeline does seem more precise when measuring speed accuracy, but I don't think I can hear a difference. Neither can tell you much about speed consistency between revolutions, though some may be able to interpret the quality of the laser dash and gleam some additional information. Both the TimeLine and KAB take time.
Regarding the issue of unknown mass: is this not also an issue when trying different after market record clamps and weights? Many people do experiment with these. I would think that a high torque DD motor could deal with this change in load better than could a belt drive system.