Hi Lc McDoom,
On the basis of the one play test we did for the post that is a tricky question to be precise about.
I took a judgement that most units that are well trained regular troops are going to be on a FS of 7-8, thus a d6 to record degradation of that rating should be more than adequate for the majority of units as a FS of 0 removes the unit. I use 18mm figures and like you I don't like markers that draw the eye away from the figures so I use 5mm (the smallest) micro dice available and I don't think having even two of the dice behind a unit would be that distracting, although I would suggest that that is very unlikely as that would only apply to those very elite units and most players concentrate on rallying off FH when they threaten to remove a unit or make it inoperative. Remember it is the army FS that cannot be rallied off and will stop units in an affected formation from carrying on the battle.
Obviously beauty is in the eye of the beholder which is why I posted the pictures of our game with the micro die in action, to allow others to make their own minds up. Personally I don't find they detract from the aesthetics of the game.
Hope that helps
JJ