The frag shells are okay but nothing to build your army or strategy around. So nope, they bring nothing really interesting to the table.
Nonsense, you can drop frag shells on the double paks while you push, an ability none of the other main battle tanks in 1v1 offer, while armoured assault lets you drop the OP as fuck IL2 loiter and instapin the enemy infantry for an easy breakthrough. You bring 2 Zis guns and the Panther has to back off real fast.
The point is: One Panther is enough to block the IS2 from advancing
Nonsense. 2 pak40s are enough to stop an IS2 from just dumbly charging ahead. Panther serves an offensive role hunting it down. It's not a good defensive vehicle due to its rate of fire. StuGG is a much better example of a defensive vehicle, with fast vetting up, low cost and pop cap and high rate of fire which cannot chase vehicles due to low speed, rotation and being a casemate.
Do the same thing as Axis with a KT or Tiger
Different units. Tiger zones out premium mediums like T34/85s and Comets while both KT and Tiger mostly stay near the front constantly bleeding the opponent hard with their main gun hitting opposing squads. IS2 does that too but its commanders having breakthrough ability call ins and the better durability of 7man cons compared to Grens and soviets weapons teams with its frag shells allow the soviet player to more easily make a big push compared to an Ost player. Ost player has to contend with more mines, has to spot the double zis to drop frag bombs and actually hit them. Soviet player has to spot the double paks, drops frag shell and IL2s and just push in. Different tanks, different strengths.