I don't disagree with you that Stalin was a brutal murderer and he is responsible by 10-15 millions deaths. By other side, Boris Yeltsin is also responsible by something like 5 million deaths (the Russian populations is dwindling by 500000 inhabitants an year), but, at least, Stalin's government achieved high rates of economic growth and industrialization while those drunk man and his Western oriented economists destroyed and looted everything they could. What I'm trying to say is that Stalin was very interesting in keeping post WWII status quo, maybe for weakness. I really don't know what USSR would do if they had enough power to conquer the world. I still think it woudn't do it, since he was a very cautious man in external policies questions, but, on the other side, unnoposed superpowers can easily become "rogue states". Your own country is a good example on this. How many people died in USA interventions and economic blockades last 10 years? How many ferocious dictatorships were imposed to Latin American people, a continent where USA hegemony cannot be effectivelly changed. I would mention Somoza, Papa Doc and the worst of all, the government from Guatemala who murdered 5% of its population in 30 years and led the country to economic ruin.
Alexandre