You seem to assume that the Bolsheviks were the principal cause of terror simply because terror followed their reign. That logic is not only lacking the counterfactual, but seems plainly faulty - by the same toke, should we infer that being taken by an ambulance to a hospital causes people to die?
A good analysis of anything, including the good old x-USSR would start with separating different effects - which is routinely done in any truly scientific inquiry and almost never in ideology that masquerades itself as science. In this case we need to separate the effect of Bolshevism from those of general social-political conditions that prevailed in Russia at that time.
There is little doubt in my mind that the latter are the root source of much of terror political terror in Russia during the past two or three centuries. The real question is thus whether the Bolshevik and Stalin rule contributed more that terror, lessen it, or perhaps made no difference at all. An we need to do it in comparative terms i.e. Bolsheviks as compared to whom? The Kerensky government? The white reaction? Here is where your argument falls short of the counterfactual.
As to post- World War I Germany - perhaps Communists did their usual sectarian stunt but at least they did not rely on the fascist Frei Korps to murder their political opponents Rosa Luxemburg and Karl Liebknech, as the social democrat Friedrich Ebert did. It makes me wonder why the post WWII social democrats selected this pathetic figure as their patron saint, e.g. the Friedrich Ebert Stiftung (http://www.fes.de/) that funds their projects.
Related topic - in reply to Joanna Bujes and Michael Pugliese who were unhappy with my criticism of the Beatles - I did not say I did not like the Beatles - au contraire. All I said that it is disconcerting when people confuse entertainment with politics. Thefact of the matter is that the whole 'counterculture' hoopla was entertainment, but some people fool themselves that not only was it politics, but worse still - politics with decisive consequences. Clearly, too much inhaling. By the same token, some main stream pundits credit 'Solidarity' for being the force that brought the Soviet system down. What a ruse!
Wojtek