but how about making it a option?
die dials can display up to 4 digits, so you can either do xx.xx° or xxxx mil
Historically most european armies implemented Mils (Artillery Strich, Streck etc...) in the late 19th century, while as you said there where outliers to it, most of them used some sort of mil based system;
early german compasses had 5760 mil for a circle
the eastern block and france used 6000mil circles, france implemented them in 1904
Sweden and denmark had 6300mil circles in that timeframe
Later down the line it was standartised in NATO members to 6400 mil
picture of a french model 1922 compass