First of all, I voted for Traditional languages, Slavonic in my case, to be used in church, but not necessarily at home in prayer, etc.
Firstly, I would like to address Father Siluan and Jean-Serge by saying that I, as a Serbian speaker DO understand very much (about 75-90%) Church Slavonic. I don't know who is always saying we can't understand it! I will demonstrate most simply the similarities between the Slavonic AND Serbian versions of the Lord's Prayer, written phonetically.
Slavonic:
Otche nash, izhe yesi na nebesye.
Da svyatitsya imya Tvoye, da pridet Tsartviya Tvoye, da budet volya Tvoya, jako na nebesi i na zemlyi.
Hlyeb nash nasushni dazhd dnam dnes, i ostavi nam dolgi nashya, yakozhe i mi ostavljemo dolzhnikom nashim.
I no vo vedi nas vo ikusheniye, no izbavi nas od lukavago. Amin.
Serbian:
Otche nash, koji si na nebesima.
Da se sveti ime Tvoye, da dodje tsarstvo Tvoje, da bude volya Tvoja, i na zemlyi kao shto ye na nebu.
Hlyeb nash nasushni day nam danas, i oprosti nam dugove nashe, kao shto mi oprashtamo duzhnitsima nashim.
I ne uvedi nas u iskusheniye, no izbavi nas od lukavoga. Amin.
Even a non-native speaker can see the immense similarities.
Secondly, I would like to also address what someone had wrote about Sts. Cyril and Methodius translating prayers into the native languages. WRONG! They translated from the Koine Greek into what became to be known as Church Slavonic, perhaps construed from the letters of the Greek alphabet, or perhaps a spinoff of a primitive alphabet the Macedonians (Slavs) already had in place. The first bit of Scripture translated by the Holy Bothers was not into Serbian, Bulgarian, OR Macedonian, but into Slavonic.
Thirdly, in the last quater century, when all this pushing for the Slavic churches to have the Services in their own languages has sort of come to head, we have also seen the Church become more and more splintered along ethnic lines.
Finally, I would like to add that I think we as Othodox Christians should be familiar enough with the Divine Services that we should know at least the Liturgy by heart, regardless of language they are presented to us. Thankfully, most of us have more than mere auditory perception-the Services include movements, and smells, and even tastes- that allow use of all our five senses to partake in their Great and Holy Mystery.
Glory to God for All Things!
Tessa