I looked at the 105 double service instructions and Shimano says to adjust the height of the front derailleur 1-3 mm above the large chainring. When reinstalling it after cleaning I set it at 1.7 mm which was much lower than from the factory. Is there a reason you'd install some at 3mm and others at 1mm? What are the tradeoffs? This is a compact 50-34 if it makes a difference.
'93 Trek 750, '92 Schwinn Crisscross, '93 Mongoose Alta
I always set the derailleur as low as possible without having any interference; I set it so that a dime barely fits between the cage and the large chain ring teeth, which I reckon is about 1mm. Check the clearance at several chain ring positions as they are seldom perfectly round or centered. In general a lower derailleur setting will yield crisper shifting, IMO.
Current 79 Nishiki Royal, Jeunet 620, 59 Crown Royal, notable previous bikes P.K. Ripper loop tail, Kawahara Laser Lite, Paramount Track full chrome, Raliegh Internatioanl, Motobecan Super Mirage.
From experiance I have found that finding the perfect FD height can very a lot depending on crankset and gearing sometimes as low as a half mm up to about 4 above the big chain ring. Normaly I just find the lowest point at which everything works good and raise it just a bit. Your setting of 1.7mm sounds about right for most setups. If you found a hieght that everytning works great at with in reason I would just leave it and stop worrying.