One of the issues I'm seeing with the pathfinder and formations is that it prevents formation movement through gaps. A good example is on Acropolis Bay (2), take 3-4 of your initial military units and try to send them down the hill toward the middle of the map. They will walk the long way around the back even though they have no problem going down the hill individually. I don't know if this is an intentional behavior to try to improve formation pathfinding, but the result is quite awful in this case. It's not clear what is happening based on the pathfinder overlay.