Benedict’s original schema, now called Benedictine “Schema A”, is still fully liturgical in the places that continue to use it. I know of at least 4 abbeys that do still use it in the Solesmes Congregation.
What was changed, after Vatican II:
Some of the hymns reverted to a more traditional text (applies as well to the LOTH in Latin)
The Liturgical Year will conform to the post-Vatican II year: Advent, Christmas, OT, Lent, Eastertide, OT, instead of Advent, Christmas, Time after Epiphany, Septuagesima, Lent, Eastertide and Time after Pentecost
The readings were made to correspond to the ones in the LOTH
The prayers were made to correspond to the ones in the LOTH
The Calendar changed and instead of the complex degree of feasts, there are optional and mandatory memorials, feasts and solemnities; however the Benedictines get to keep their calendar with saints.
Here is the relevant paragraph in the General Instructions:
The MD will comply with the current Benedictine schema A only in the order of the psalms. So as I said earlier you could use it paired with the LOTH. You substitute the psalmody from MD instead of the psalmody from LOTH, but you take the rest from LOTH. The Office of Readings is a special case, it replaces the Night Office. To do that on the monastic schema, you’d need a nocturnale. But you’re fine just doing the day hours. After all you’re an oblate, not a monk
The only thing you’ll have a problem with using the LOTH is the memorials, feasts and solemnities from the Benedictine calendar. They are not in the general Roman calendar, and there are other issues, for example although the St. Benedict appears in the Roman calendar as a memorial, for Benedictines it’s a solemnity.
Like I said the LOTH can get complicated! I once wanted to celebrate the feast of Sts Placidus and Maurus which appears on Jan. 15 in the Benedictine calendar as a memorial but with a proper office (therefore, like a feast with festive psalms and proper antiphons), but doesn’t appear in the Roman Office (LOTH). As I chant the Office, I needed my Roman antiphonary, the Monastic Antiphonary, a hymnal, a Monastic breviary for the prayers and common of monks, and it was very sporting indeed flipping back and forth with 4 books. Next time I think I’ll just say the collect for that day.
So the MD is not a waste:
- you can still, liturgically, pray the Benedictine Office as it is an approved office for the Benedictines;
- The MD, while out of date for the rest of the Office, does have the correct psalm schemas for the Benedictine Office
- Therefore using the MD for the Psalmody and the LOTH for the rest will allow you to join the Church in her liturgical prayer of the Divine Office.
One last caveat, in case folks who do the Monastic Office in Latin are checking into this thread: if you have an older pre-Vatican II Monastic Breviary, the psalms will be in the wrong translation, they will be the Vulgate translation whereas in the post-V II Office, the Neo Vulgate is used, and even since then there have been changes. To be “up-to-date” one needs to use one of the Post-Vatican II Solesmes books: Psalterium Monasticum, 1981, or Antiphonale Monasticum I, II, III and V, 2005-2009 (Volum IV, the night office, is supposed to come out this year)