It´s good for nothing. Can´t tank since it has a mediums health pool, can´t be spammed since it´s one of the most expensive units in the game, can´t outrange a lot of units and can´t even out-dps a fucking Panzer IV.
Don´t build it.
The only-allied expert team is coming for you though since you proposed a buff to a German tank. Pretty tired of arguing against them again. Have fun.
Panthers are basically easy mode the tank destroyer, smoke, speed, range, health and vet 2 armour better than heavy tanks. It's cheaper than the comet and utterly destroys it 1vs1 stock, let alone once you gain vet (Comet vet gives you nothing but AI abilities and mobility in comparison).
Really the only downside is the meh reload and moving accuracy, but when you factor in the extra 10 range and 100% pen against allied tanks with the above points the unit is balanced.
Try the panther+command tank combo some time, spotting scopes too.