It would be helpful at times to not have the units auto-converted. For example, I may want to see a distance as 1012 meters instead of 1.012 KM.
Usually this is because I am thinking in terms of 3D unit space and not so much of actual distances. Also, when converting from Maya to Clarisse, it is annoying to have to try to read not only the number, but also the unit and then do a mental conversion to compare values.
Doing the conversion isn't hard, but it IS an extra mental step. If I am comparing two values, and one reads:
9.9 cm
and the other reads:
1.0 dm
It always takes an extra beat and tiny bit of effort to compare the two.
Whereas if I read:
9.9 cm
and
10 cm
I can compare them with less effort.
So I would request a preference that allowed me to set all of my distance and area unit displays to always display in the default unit, with no conversion to higher or lower sized units that are "human readable".