The price of ammo would be my major concern. .308 Cost a lot. 5.56 only cost 6-7 dollars a box for brass cased, even less for steel. That has to be at least twice as much training.
I reload so cost of ammo isn't really much of a factor. We're talking 40-50 cents a round for match grade stuff. We're not talking about heading out to the woods and laying down covering fire.