Yeah, I have been avoiding drilling the idle jets for these reasons. I have heard that Weber actually flow tests (or did flow test) the jets to make sure that the combo of jet hole, taper, air bleeds, etc makes a 50 behave like you would expect a 50 to behave, not that it has an exactly 0.50 orifice.
I do wish I could find .52 jets somewhere though. I have seen them listed on old Weber literature, but can't currently find them. Short of finding some, I may have to start experimenting with drilling out some .50 jets.