I only played one match on this map where there were around 22 players, so I'm not sure if my observations would hold up in a smaller map. But in the one match I played, it seemed like barely any damage was done to either the Advanced Naval Yard or Advanced Subpen. This made me wonder if the base defenses were truly necessary. It may very well be that they are in smaller games, and it's only because there were so many ships that no one could pull off a good attack.
On a similar note, do you think it would be possible to make it so Attack Subs could damage turrets? Gunboats and Destroyers can both attack Flame Towers, but the Attack Sub is completely defenseless in this regard. I'm not entirely sure what the range on subs and turrets are, but as long as subs don't grossly outrange turrets or anything, I think this would be a good change.