I really, really like this idea. I've almost always tried to mentally calculate how well each side is doing at each point in the fight, and it is hard to do so without putting in a lot of time.
One improvement I'd like to have that goes along with this idea is:
Also indicate how many of each type of unit were lost by a side at the end of each round:
Round 1: Side A lost 22 archers, 7 cavalry, 20 Mixed Infantry, and 50 infantry, Side B lost 10 archers, 20 infantry.
etc...
