There's really nothing to argue one way or another. It consistently gibs entire squads regardless of vet in the blink of an eye.
That's it - end of story.
It doesn't matter if it costs 4000 MP and 8000 fuel. It doesn't matter if it comes out at the 45 minute mark. It doesn't matter if it's 12CP.
This is Company of Heroes, where unit preservation and veterancy and combined arms are key. Anything that does what the KV8 does, with small exceptions for lucky artillery strikes, completely breaks that aspect of the game.