This might be off-topic.
You both make good points about PZIVs and JPZIVs being more viable, BUT:
Correct me if I'm wrong, PZIV is outclassed by Jackson (180 armor meaning around 90% penetration at max range). JPZIV is a bit different, although it has good armor (230 meaning around 70% penetration at max range) and it also has a small target size, so if the shot hits, it most probably will penetrate. IMO, these dedicated tank destroyers should outclass medium armor, YES, Jackson should beat PZIV at max range, and it already does. So, increasing the penetration (and also reducing damage a bit so the poor PZIV has a chance to run) would not do any more harm. Although a well microd PZIV might get the Jackson off-gaurd and kill it, which is a reward for microing your tank well.
About the heavies being slow, you have a point there but it's hard for USF to flank a KT. If your enemy is not brain dead, there is at least another unit to support the KT. A Schreck Blob or their teammate's PZIV or PAK. So, TDs should counter heavy armor from far away, frontally.
In a balance utopia, you find use for each and every unit in the game. But you can't expect your StuG to counter the Jackson. If you see Shermans, you go for StuGs and PZIVs. If you think they might bring in Jacksons, you go for Panthers and other heavies.
PS: Still believe that the Blitz is the major problem.
The P4 is CRUSHED by the Jackson similar to how an Elephant will crush a T34. As USF its hard to flank anything. Since 9/10 times the highest HP Pool youll get is 640. And most are below that. Flanking is punished Heavily. You need to ENCIRCLE to receive any reward as flanking can still result in a front hit.
In Essence trying to flank in 90% of cases is a bad idea.
So the Jackson must engage at Max Range where its DPS and its Pen is the weakest.
The Panther on the other hand like an LMG can just A move. Seeing a Pattern Here? Shreks A move, Obers? A move Panther? A move.
Because its too fast to be encircled and too much armor and HPs to be killed frontally unless you just suck or the RNG gods hate you.
Blitz is a problem but I would say the Armor/HPs are a bigger problem. I honestly have an easier time taking out a KT then a Panther. Because things can escape the KT. Its big and its slow and GOD HELP IT if it takes Engine Damage.
An Engine Damaged Panther using ROAD BLITZ is faster then most tanks who are not also on a road. So Engine damage is not punished on the Panther as its still fast and just needs to reverse.
If people dont want the reduce its Armor for lore purposes FINE! 640 HPs. DONE.
There is no need for it to have more armor then a Tiger and More Speed with More Range and almost the same amount of HPs arriving at the 12 min mark in a 1v1.
USF needs AI armor to deal with things like Obers and Officer Backed G43 Pfuse. But the Panther punishes that it makes the unholy OKW Trifecta. Shreks, Obers, Panther. There is no weakness in that build. Only Strength.