The only thing I'd change about the Ottomans right now is that I'd make the yields received scale off something instead of just being flat (I know they scale with eras, but they are still scaled flat yields, if that makes any sense). However I have no clue how to do such a thing, but it would probably make a lot of the existing flat yield UAs more fun. Maybe somehow compensate for how much longer 30 turns is in the late-game compared to the early-game. But again no clue how to do this. Other than that I really like the Ottomans.