Sandberg,
I am not the best one to respond to this as I am still debugging my setup. I have a homebuilt router and so far in my calibration tries, about the best I can achieve for isolation is about .13mm (~.005") using a 30° V bit on my homebrew vacuum chuck.
My spindle is by Paul Jones Engineering and I don't find any detectible run out. I also use an "autoleveling" software package to take care of the variations in board thickness.
In my estimation, you will need not only an accurate, repeatable platform, but a very stable spindle with no run out and use a finer bit that I am using. V bits are not to a sharp point and depending on supplier, will have differing tip sizes. Even then, you will need to calibrate each bit before using it.
Hope this helps and look forward to other peoples thoughts.