About 800,000 loyal Bolsheviks were killed by the Stalinists in '37 and '38.
Mensheviks would not have done that.
Until the late 20's there was still great potential in the USSR. After Uncle Joe started to consolidate, the chances to reconcile Leninism w/ revolutionary democracy were smashed. as y'all know some date it earlier to the banning of factions in the Party like the Workers Opposition. See Robert Daniels, "the Conscience of the Revolution, " or Robert Conquest, "The Beginnings of Communist Autocracy."
Dustin of history, eh?
As a counter-hegemon, the USSR did restrain the USA though. But, as E.P. Thompson said there was a cynical we have ours you have your zones of the world to dominate logic/game to the Cold War though. See, "Exterminism and Cold War, " the Verso collection w/ Thompson, Halliday, Mike Davis and many others.