I am sorry that I answer so late.
As for old USSR amphibias - I have 2 and they both work perfect. Of course they are after cleaning and oiling. The watchmaker told me that due to quite large crown it is quite easy to break the spring so the watches should be wound carefully. having this in mind they should work properly for ages.
As for new russian amphibias I heard that they break down much more often. Ca 30% of such watches of my friends needed to be repaired. Fortunately the defects were not series. It is strange because these are the same mechanisms. I supposse they are made with less attention as for quality.
I am sorry my English is not very goog and that I cannot answer in Czech.