I don't mean to sound dismissive, but has anyone got a good enough eye to distinguish between 2.7 and 2.8, or 2.8 and 2.9mm?
Even if they have, considering you've also got a variable string height depending on where it's fretted and how hard you hit it, plus a set of polepieces which can also be micro-adjusted if desired, plus magnets of different strengths, plus the effect of different string thickness, composition and tension, plus a bridge radius which could be anywhere from 7.25" to 16" or something.... I don't see how set-up can be narrowed down to the nearest tenth of a millimetre.
Sorry, but that just seems crazy to me. If it was "start around 2 to 3mm then adjust to taste", fair enough.