At the end of the day, OO just slightly better at fighting near seas and way worse at everything else.
No, they are dramatically more powerful in coastal conflicts. It's just that without those conflicts they're, as you say, way worse and, also as you say, coastal conflicts are quite a gamble. One you generally lose against humans.
rocklikeafool said:How big are your armies that you need the massive economic support of RoK? FfH (and its modmods) are not designed for the human player to be building massive armies
On Deity and playing any civ without 0-maintenance or limited cities, it's a tremendous advantage being able to run at or near 100% research. Even at lower difficulties, surplus gold pays for unit upgrades, AI bribes, mass-purchase of equipment like healing potions or plate, and expensive events.