The OKW Panther costs as much as any Soviet tank and the Ostheer Panther costs more than like 2 1/2 IS2's to even build lol.
Why do I have to keep explaining this.
Teching cost =/= unit cost.
Teching cost affects timing, and has the same effect as CPs. However, tech costs generally give you access to multiple units.
You aren't paying all those tech costs to get a Panther, you are paying those costs to get Ostheer T1,T2, T3, and T4.
You can also get more than one Panther at a time, unlike with a doctrinal Heavy.
To put this in practical terms, what you are saying would be like arguing that a Jackson squad costs 285 fu now.
Back on topic, why is the E8 having 800 HP and 160 armor OP? It will merely be less easily killed by Heavy AT, more easily killed by panzershcrecks, paks, and panzerfausts.