From what I saw when it was first released, it was a pretty stupidly high powered weapon..
Also, taking your point "How can I know if a weapon is overpowered if I haven't used it yet?" Isn't it also true that it could of been absolute dog**** and you'd have still wasted 75k on it hmm? So in which case you'd have still complained about it.
KSG seemed to dominate in most circumstances, thats why it was reduced a little, pretty sure rather than blocking every bullet it now blocks a % of bullets to even the playing field..
Now, what exactly is wrong with the KSG? No one seems to want to tell me what is wrong with it x.x Is it too slow? Too low damage? Blockrate too low? Freeze to high?
Throw me a ball and I might throw one back.