pretty much the same as ISU plus 10 range plus minus immobile during shoting. You can exploit the opponent for so long, until he catches you with your pants dawn during a panther dive. Imo too much drawbacks. I could see that work, if SOV had pak43 alternative (or theoretically a convenient UKF ally)
I'd say both IS2 and Kv2 has 2 good commanders, but the is2 has the "get the F of my lawn" loiter, radio intercept and t34-85 for the mid game, also IS2 is considerably more responsive. KV2 has the windustry lady for fast repairs, resource trucks, KV8 and pretty fat AOE on the heavy tank.
Maybe I'm sleeping on the ability, but it is extremely situational and requires too much setup to be executed. Not saying it is useless, but a strat for the KV2 long range setup has too many holes, like lacking mid game power (if you skip t34) and too much AT (I suppose you also skip KV8, since you personally don't like the tank). Perhaps it may work if you survive til lategame and manage to get your perfect "snowball" build, but I haven't seen those. And if the guy just backs off a little, you have to redeploy and pray that the Axis guy is not tryhard enough to pick a heavy TD commander.
ISU is much more convenient in this regard: "Mark target", guards and sneaky AT. AI strafe is also pretty decent.
Having a T34-85 is a big bonus though. It's probably the best doctrinal medium tank, given it's performance/price. Not only that, but it can be used in the same way the Panthers can, in teamgame lategame: Hail Mary push. You could do it with a Comet, but given it's price and AI power, you won't get far. Sure it will bounce a few more shots than the T34-85 but still...
That's one massive argument in favor of ISU if you ask me. Of course, your arguments concerning KV2 chunkiness and the fact that it comes with another AI heavy tank, the KV8, renders the commander generally unfavorable.