Considering how unpofitable the high tier economy is the skill spread may be skewed heavily compared to CBT. As Spoon mentioned, there are some torpedo concealment buffs and BB turning nerfs in the pipe so it might improve. Once I finish with the ranked season I think I will probably concentrate on the Fubuki and see if I just was having a bit of a funk. Kagerō was my absolute favorite platform in CBT, I will be sad if she is pants in the current meta.
As for upgrades I always kept the extra turret, AA on IJN Cans is useless, stealth is everything. If a CV decides keep you lit the extra AA isn't going to scare him away. While you lack the traverse and RoF of the USN DDs their shells only come back down due to orbital decay while yours shoot nice and straight. With the full turret arrangement you throw more shells in a salvo than similar tier US Cans save Gearing and can kite very effectively due to the arrangement. Played right you can win gun duels with US cans, and its extremely satisfying. In addition the extra guns are useful when you need to finish off a wounded ship that your fish haven't quite kill.
I haven't faced enough VMF cans but on paper they appear to be scary as **** though.