I guess you are right with not noticing the difference between 5 an 1µm
But with the box open an having the manual I guess you can change between 1 and 5 µm per jumper setting. But not sure just a guess.
If I have 5µm resolution on the scales now I will change the Z axis my 3600 line encoder (bought this for the spindle, but the new motor hat its own) I have here instead go the 5000 which is in there right now. I its 1µ m I'll buy a third box.
Not sure what to do with the A Axis, this will be a project for later anyways.