Also, pure communism, enlightened despotism and all other political ideologies that require top-down control, seem to all have the same failure mode. The violence is a side effect of the authoritarianism, not the economic model (I think). More democratic societies have fewer and less lethal political purges. I don't know what a fully democratic pure communist system would look like but I'd be very interested in seeing how it played out.
Maybe it can't exist as long as there are those who seek the aggrandizement which leads to a consolidation of power. If you have a state that owns everything, there will be people that will abuse such authority. Could there be a communist economic model alongside a multi-party state model?
Communism Light, all that great communism flavor with less murder (so far)