Very interesting but the polyphonic music is so common in slavonic and Russian countries... The only country that I heard monophonic music is in Romania, Bucharest
I am afraid that many chanters in Romania use simply "monophonic" music (given that most chanting books are published in double notation-psaltic and linear). Of course there exist notable exceptions.
Another issue about which some colleagues from Romania and Bulgaria are complaining about is the trend to hellenize (and oxidize as one mentioned due to the use of the "oxeia") the existing psaltic music. Some melodies are bizarre for us (eg the chanting by the Romanians of "God is with us" in mode VIII irmologic from Ga or the Great Kanon Kontakion in mode VI sticheraric by the Bulgarians); yet I doubt that the substitution of these melodies by those used in Greece will greatly improve psaltic music in these countries. On the contrary it might become a stumbling block!