The referendum results are interesting. Estonian independence referendum results division matches closely the ratio of natives and civilian population of that the occupying power(USSR) transferred into the occupied territory. Same with the voluntary referendums organised by pro-Soviet front-organisations. The count of voters is close to illegal occupant's population. We were lucky. After breaking free we did not suffer such harsh conditions as you have mentioned(Gang leaders elected as mayors and governors who murdered anyone who dared to oppose them.) Economy boosted and living conditions improved drastically every year.
We can safely establish that part of the soviet union wanted to stay together and part of it did not. And the results varied drastically country-by-country - nation-by-nation.