Doug,
glad you could improve your focusing experience :D
About the uncertainty: It is linked to remembering in which direction the last focus move went. That means as long as the EAF is powered(*) it will not lose steps and all positions should be absolute and repeatable. Shifts only occur if you, e.g., do the last move outwards, then power cycle the unit and reconnect. IIRC it will initialize with 'focus inward', and your next move command would introduce an error of 1 BL value. At least that what my conclusions were when watching it.
Since I switched to using Linear AF basically all moves always end moving 'inwards', and focus values are stable since then :)

(*) I think it is the EAF, but it might also be the driver. Not really sure...

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