Played about 30 games in Duca, I think my WR is about 60%, which is plain average I think.
Main problem with Duca is that we don't know how to use it.
It is fast so you get easily in front of your teammates and you are submarine in a moment. So control the speed, don't just go full.
Second thing is main battery range. With my MM which is 95% of time with T8 (yes I don't like MM and blame it for less fun in this ship), 14km guns are no fun. So you need to choose targets carefully, don't get detected all the time. I have no favorite - both HE and AP are less productive than my other T6 ships. And I really miss a km or two on that range. With that, my games will be much more fun for me. WG, we are here for the fun, right?
With 11,7km spotting range it's not easy to do what Duca is supposed to do best - hunt for DD. 1 on 1 Duca is just DD nightmare, but if there is another ship or two, it comes all the way around. My captain is now on 10 points, two more to get better concealment. And another four to make him as I would like him to be. Guess I will have to wait for all that to have second opinion.
After 30 games in it I still feel like I need to learn a lot lot more abut it. So, mount Patience module on you and try to have fun