Ive been thinking about T1+2 soviets quite a bit, giving early aggresiveness, followed by T2 stability.
I know a SC paired with the engie can be really good, Just seems like a lot to build T1 just for one SC?
So may as well do the same with either guard motor, or if you dont need guards, use Armoured Assault..
It may seem like it's a lot to get t1 just for M3, but I really think the early M3 is worth it in this patch. It can kill grenadiers pretty quick if you keep it at range. And pios can't do shit to it. Once you get a flamethrower you can start wiping retreating squads like it's nothing.
Additionally, you get a lot of intangible value by forcing them to turtle up or travel in groups. Against early M3 you can't send your pios out to cap alone, which allows cons to swarm the map and get great map control. This effect is increased if you can get an early squad wipe so they can't contest it. I personally think if you use it right you can cause enough mp bleed and prevent enough capping to make it pay off for itself and the T1 building.
And you're right, Armored Assault is probably better for T1+T2, but I don't own that commander unfortunately. Plus, I personally prefer the Sherman over the 85 for it's better anti-infantry if you have the option for ZiS against heavy armor.
And I hate Guards. They always seem to underperform when I use them, and you don't really need them when 2 at nades can kill a 222.