Given the 26% premium on Fireflies over the cheapest Shermans I don't think that is quite accurate. The same dynamic is present with a US opponent, where the Sherman 76s are even more expensive than Fireflies. Cheap TDs like the M10 and Hellcat are an option but they come at the opportunity cost of very limited anti-infantry capability.True that the German player cannot choose Fireflies, but it's no good trying to surprise an opponent by a value strategy when his strategy remains better value. You won't catch any Allied opponent on the wrong foot by choosing Panzer IV's.
That is extremely rare. Even at 300m you are more likely to get a ricochet penetration through the hull roof than a direct penetration through the turret (at least on Panther A, maybe not on G).A Sherman 75 can knock out a Panther frontally at 450-650m through the turret (firing regular AP). And since the game highly favours turret shots, and most combat in CM takes place at less than 650m, the Sherman is far from defenceless.
I maintain that Panzer IVs are a good choice for the German player in almost all circumstances. I know some people (not me) think they are too expensive but they are cheaper than the 76mm and 17 pdr Shermans players are most likely to buy because Panthers.But yeah, against a US player, at least there is a kind of balance where the Panther is tough and expensive, and the Shermans weaker and cheaper. It's mostly when you add the cheap UK Fireflies to the mix that the balance goes out the window because the German player has no real counter. If defending the German player can sort of counter them by stocking up on Marders and PaK 40's, but in an attack or meeting engagement I don't know.