I wouldn't call the panthers gun a dud but it sure doesn't do much to infantry but yeah the comet definitely wrecks infantry really hard to the point where I dont think either of these tanks costs reflect their performance.
If you are gonna be hugging cover when fighting an AOE tank, you are gonna have a bad time. Meanwhile, if you hug cover against an accuracy based vehicle, you will be fine. Example: T70 vs Luch.
AI from Comet vs PV is EQUAL when they are out of cover with spread out unit formations. But when you have squad which like to hug to each other (Falls for example) you'll have a bad time.
This also means that PV AI can be mitigated by using cover at oppose to Comet. There's also the difference between prolonged damage and alpha damage.