This strategy is mostly like the strategy I have concluded. I would, however, like to add a few points that may not be right, but hopefully worth a thought.
Against the Puma, I like teching to T4 immediately and getting a SU-76. This is for the following reasons: First, a well microed Suchka can defeat a Puma quite easily, especially if coupled with a vehicle nade from the Conscripts. Second, it is not as expensive as a SU-85 or a T34. It costs like half the fuel, which is especially important if the Puma is already around and preventing the Clown Car from spreading love. And last, the SU-76 offers more flexibility than the SU-85 (not the T34). It is faster and, with its artillery ability, able to combat infantry effectively. Especially the last thing is important, as the SU-85 can do nothing against a blob of Sturmpioniers/Fallschirmjägers/Obersoldatens. Now one could say, that with our infantry punishing strategy, this would not happen, but if our strategy does not work 100%, its quite possible.
On the flamer Penal squads vs upgraded Conscripts, I am a proponent of the flamer Penal squad. In addition to the points brought by theblitz6794, the flamethrower is already active at medium range and does ignore cover. If you have to clear a Sturmpionier squad standing in green cover, walking your PPsh Conscripts into them is much more dangerous than flaming them from medium distance. Pretty much the same is true against units in buildings, at least if we do not get Molotows.
As for doctrines, I play this strategy often with Shock Rifle Frontline Tactis(Shock troops, AT stealth, flame arty, KV-8, IS-2). Not so much for the first two abilities, but for the last 3. The flame artillery takes care of any MGs, Raketenwerfers or infantry blobs, while the tanks pack quite the lategame punch.
