Actually the JP4's gun has the penetration as the StuG's, 60 less than the Panther's. It was the same gun in real life, but it's much weaker in-game.
Real life is what I was referring to. 75 l/48 is the stug, hetzer and late pIV, l/70 was panther and jpIV. At any rate OKW has a great TD and they also have the Panther, both stock. And now a quality stock medium. Fairly solid AT gun. Doctrinal Pak43 and Jagdtiger. Shreks on their core inf. Not hurting for AT options at all. I really think a flamethrower tank would be a more interesting inclusion for the faction.