The JPIV 'counters' tank destroyers with its Vet 1 and Vet 2 bonuses: Vet 1 gives it cloak so it always gets the first shot off, and Vet 2 lets it take another hit.
Those are both big advantages in a slugging match.
It does, I never question the ability of JP to zone Allied TDs (getting a kill is another story), is simply pointed out that is has a similar cost/pop while most counter are cheaper.
Simply nerf the unit in anyway seen fit and reduce cost to 300-350MP 100-120 FU. Then it will be inline with other counters.
The unit got a higher tech cost while remaining at the same price and also got nerfed (probably justified), the units performance does not justify it being more expansive than SU-85.