According to coh2db.com zis and su76 already have same pen. But different damage.
Ost has teller for free and axis have better hh at in damage and pen.
You are forgetting that the panther starts at 260 armour. Hihgest soviets non doc is 150. Usf is 160. Churchill and comet are 240 and 290 for ukf.
Pen for the zis/su 76 is n/m/f 200 190 180 at vet0. At vet 3 its 260 247 234.
Pen for the pak is n/m/f 210 200 190 at vet 0. At vet 3 273 260 247.
No consider the armour values and wich at gun is actualy overpreforming now?
You have to look at the hole scenario.
e.g. Panzer 4 vs T34. They have same HP and will need 4 shots of AT-gun. Whay one of them is more expensive? Because it has better stats, but the advantage isn't really present. Panzer 4 is slower and also engine-damage is a larger disadvantage than for T34. Beside Penals makes a way better supporter of Zis than Grens or Schreck-crews for PaK40 (which simply gets steam-rolled by a good T34 micro).
Not saying that a good used PaK40 is bad, but as line-up it is worse than Zis, which still can be used to kill support weapons or desrtoy Bunkers, while having 6 crew-members and the option for merge. Simply can used as non-brainer unit while.
Overall, OP. OP in the hand of somebody understading the unbalanced game and uses merge.
And I don't want that CoH becomes a AoE clone, everyone building the same orders. The game becomes stupid at the moment. It can't be balanced if the micro-managemet and options of one fraction are overall worse than of the other.
And Panzerwerfer is one unit of the hole, it is worse than Katjusha. Has the bonus to suppress to hold points. If it woulnd't have that option it would be more clear how bad the line-up of Ostheer is. xD
Edit: Simply look more at CoH1, the tank/AT-gameplay was way superior to CoH2.