THats, what I did, and to me, I rock in a D40, I killed a O-pro with 1 on 1, and killed 5 Q's all by myself, guess they were all noobs, they can't hit a thing, especially that BB.

I use SP40 for support for All welcome.
I ll equipe with AA gun for defence of BB and CV
and torp for sink DD or CL

the spahkreuzer can be remodeld into a cl at lvl 27 or so. THen u will have a plane, some more armour, better sighting and bigger guns. But for cl standards the ship sucks. But as dd it is very powerfull. and has 3 support slots.
The cl version can carry the 6.75 n with 2 binds of ammo too little. so if you go to the d version u get 3 binds on the dd version. Enough for a good battle, besides u still have dd status and get extra exp for killing cl's.

after u remodel its a CL1 NOT A DD!!!!

Sure with the remodel you get more FCS space more displacment, higher durability and bigger gun turrets. but best of all you can fit on 1 plane which for a DD is remarkable.