From my point of view there's nothing wrong with the su85, it's just extremely high micro-tax to keep alive and make use of, also after getting vet 2 it becomes a machine gun and is able to take down panthers with some infantry support
Maybe it comes a little too late and the cost-effectiveness isn't that great, dropping the cost to 300/100 would be fine imo
The point made about it having bad pen, it trades penetration for a greater rate of fire, this makes it a beast against PzIVs and other tanks without higher armor but still allows it to deal with heavier tanks.
(sarcasm) And Brummbär? It's the best unit in the game Kappa
(/sarcasm)