Is "oi" always pronounced as "i" ("ee") in Greek?
So, it's not "metanoia," but "metania" (or "metaneeya")?
According to my understanding, there are three broad types of pronunciation:
1) Modern pronunciation: used in the Church even for Koine words
2) Erasmian: an early attempt in the Renaissance to establish the "original" pronunciation based on comparing poetry (what would rhyme with what?, etc). This is taught in many Classics departments
3) Reconstructed: what Ancient Greek would have probably sounded like based on linguistic evidence; has a lot of the Erasmian pronunciations but goes further and has aspirated vs unaspirated p, t, and k (modern has f, th, and x) and the accents are tonal.
So yes, it would be me-ta-neeeeee-ya