Though an interesting (and I guess slightly more realistic) move might be to increase unit sizes (something off the wall like 300 or 400 guys) but let you control fewer units (10 - 15). I know in the American Civil War (which is far too late for Empires but it's the only period I have information on this) USA regiments were supposed to have 1000 soldiers, and usually had less than half of those ready to fight at any one time. If the numbers for regiments are similar in the time of Empires, I wouldn't mind losing in numbers of units for a gain in soldiers per unit.