Im a eingeneer (even a mechanical one) and dont jump up the walls!
computers dont get units. Infact if you never told you engeneers the unit is cm they wouldnt mind bevcause quite frankly theyd never notice the difference.
Infact im working in company that has to add units to the eingeneers liking, the poor sods realy think their life becomes easier by this task, but thing is it isnt going to get. I can see the implementation and i can say that all its going top do to thhose poor bastards who dont undrstand computational scienses is more headaches.
If the internal unit is allways unit X its easier jut to call x whetever you like, thisway atleast you have a chek on the precicion.
set the base unt to km or Mm and see maya viewports starting to disort the models 
Thing is no computer program ahs units just numbers.