Test the spread ur accuracy gunner and crew on test mission to get some idea on how good ur gunner/crew now.
Weakness; in Blitz against small rushing fast ships... 2 or more closing in on u, u'll be sunk in no time... Stay afar and shoot bigger ship with it's 3x11"/52 SK C/28' (CA and above)... If u want to have fun use the 3x5.9"/60 SK C/25 to surprise those DDs... Never ever put dual gun on Deutch...
In GB play as AA ship, some say it's 'poor man' Motlke AA, when oppotunity come go forward and shoot anything in range. Back then I mostly play it as AA ship, due to my 11/11 gunner at level not good with 3x11" spread...
On the long run PS line is the KM AA ships to level crews (Ppro), at higher lv they have speed over the bizzy line and +1 more support...