just because something isnt popular in the current meta doesnt mean it should be ignored balance wise.
as I said in the OP a soviet player used an isu152 to come back completely from losing control of the map to a german player in the TFN langreskaya finals
I put 1v1 in the OP since thats what I play, but im sure it pops up often enough in team games
Oh I play 2v2 fairly often with a friend, and I pick the ISU doctrine if we've had equal fuel income with the Germans. Yes, it's a potential game changer, but it almost never comes out fast enough to do anything. By the time you can amass that many command points and fuel, the game is likely over. You'll need at least one SU-85 first, so yeah... good luck getting that much fuel. The thing SHOULD be powerful for its cost. There were quite a few times in CoH where the tide was completely turned when the Germans fielded a King Tiger or Jagdpanther. Elite call in units should be game changers, especially if you allow your opponent to amass that many resources.