Make Jackson doctrinal and im fine. Imagine Pershing + Jackson behind = gg
SU85 + IS2 has been possible since vanilla COH2. Or the Panther+Tiger combo. Long range tank destroyer + strong heavy tank. It's only a balance issue if the Pershing is OP. If a pershing was 240-260 fuel it would be extremely expensive to field with a 125 fuel, very fragile TD. There's also the question of AI vs AT power, the Pershing could
also be a primarily AT vehicle, meaning it ends up vulnerable to a Pak or infantry based AT strategy, which the Axis is uniquely suited to field given that they have the best infantry AT and the best AT gun (Wehr).
The Pershing doctrine would also possibly be weaker than others early on. No M1919s, no Airborne, no Assault Engineers, maybe a mediocre arty strike. People are saying a Pershing would wreck balance but it is
entirely dependent on how it gets implemented. A balanced pershing is 10000% possible in 1v1 context.
In a 2v2 context, it's an even stupider complaint since IS2 + M36 is already in use. Double USF is pathetic in lategame though, and the Pershing would make it theoretically viable (assuming its a decent unit).