Yes, I know about 3rd prehistory as mobile medium mech unit, ;) but after a FCCW they had took in their TOE survivors from 5th DG, which been a generalist, all class of mechs unit. It's a very nice pretext, which can allow more uncharacteristic mechs for DG unit, which still not the DAG. ;D
And 3rd CO in Jihad had an Atlas, 8D to boot.
Medium and lights companies (as been decided year ago) will be added next, because they demand more attention, and more accuracy.
Salvage is a good pretext also.