The SD-2 are overpowered and supposedly should get fixed sometime. But having said that, they're probably the best guns for most of the ships that can use them (i.e. Tashkent, Bogatyr, Pallada T slots and Svetlana).
People who use BB1s in blitz, especially AW BB1s, are doing it because they can't win in smaller ships. Don't be those people.