The most common Divine Liturgy celebrated is the St. John Chrystostom's version. He shortened the original from four or five hours to one hour and a half in the 4th century, retaining all the seential parts of the original.
I don't know much about St. Tihon's Liturgy but maybe MarMema can elaborate.
By contrast, the Roman Catholic Mass has been changed many times, and from what many are saying about the Vatican II, the latest version is but a pale resemblence of the Tridentine, which is but 500 years old.
Wrong. The Tridentine liturgy was just the codification of the way Mass had been celebrated at Rome for centuries.
Ironically, several of the "innovations" in the Roman Liturgy that eventually became the Tridentine Rite were introduced by Roman Popes of Greek liturgical background! The one that comes immediately to mind is the Gloria in excelsis deo which is close to a word-for-word copy of a hymn in the Byzantine Orthodox service of Vespers. And the Kyrie eleison didn't come from Ireland, either. :-)
So, as far as the development of the Roman liturgy in the first millenium, I guess I could say, "Yes, it changed and developed ... and most of that was your fault." :-)