In CoH2 the Panther is currently perfectly balanced. Previous patches showed us how useless it can become if it is turned down (even slightly).
It needs mobility as it lacks the range of other tank destroyers. With 60 range one could consider giving it less reverse speed.
So better don´t touch the Panther.
In previous patches, it has been showed that panthers coming out too early (like Ostheer once being able to go straight for T4 + panther fast enough to counter first armor) created issues. Also, in past patches where the panther could be "bad", Soviets were worse. Other than Windustry times and sniper clown car.
As for the second sentence, i would argue why it would have so much armor if speed makes up for having 10 less range than fragile armorless Allied TD. A repricing to go with that if need be.
Regardless, im an advocate against ROFLblitz creating 10 reverse speed (as in... They arent french tanks - thats a joke, not supposed to be offensive). Besides, this game isnt advanced enough to have a separate reverse speed, the same for side armor. So immersive...