On an even headcount MU between Vlandia and Empire, Vlandia would win 9/10 times. Cases like that, I think Empire would benefit from having more numbers to make up for their weaker units, especially since they seem to be designed around having a weak army that has far more soldiers than they do the weapons and armor to adequately arm them.
The Empire, weak ? With all these wonderful javelins, menavlions and the great legionnary class ? They are definitely not weak. I always have a blast playing the Empire.