(one note, I noticed in Greece that everyone bowed at the waist, or at least their heads, and remained dead silent during the Anaphora/Epiclesis, I would love for this to spread)
This doesn't happen in the States??
I haven't been to Greek Churches, but I don't see this in the OCA parishes I've attended.
In our OCA parish, the congregation fully participates in the Divine Liturgy, to include the anaphora and epiklesis, which are said/chanted aloud. This includes (a) singing the amens with the choir and saying the amens with the deacon, and (b) crossing oneself and then bowing deeply so that the right hand touches the ground after each amen. Some folks (like me) bow down and stay that way throughout the epiklesis, while one person prostrates himself. Like Paisius said above, variations are not so bad in this instance. However, since I am now used to full congregational participation, I think it would be hard for me to go back to the passive mode.
PS: By full participation, I mean that the people sing along with the Choir for all the hymns and responses; respond the the priest's "Forgive me brothers and sisters" with "As God forgives, so I forgive;" respond to the priest's "Christ is in our midst" with "He is and ever shall be;" and respond to the priest's "May the Lord God remember all of you in His kingdom, now and forever and to the ages of ages" with "Your priesthood may the Lord God remember in His kingdom now and forever and unto ages of ages."