One change I wouldn't mind is them getting the cothon earlier than celestial navigation, or maybe their capital just gets to build one for free. And the bireme doesn't have any way to shine. It's not like we'll be taking out a bunch of coastal cities or city-states with it, since both of those tend to be rare. Maybe if you have pirate problems, but they layout of the Seven Seas maps I'm playing doesn't really lend itself to that, because ironically the map is mostly land (which is why there tends to be more space between civ's).