Well, the someday came sooner than I thought, because this past Sunday at all the Masses the Gloria from the Missa de Angelis was sung (hitherto we had been using some English Gloria that was based on the Missa de Angelis Gloria). The pastor came out before Mass, announced that we were going to start doing this Latin Gloria, and then gave an excellent little summation of why we were doing it, which can be summed up in two main points:
-Latin was never meant to be abolished after Vatican II and this is how we ought to be doing the Mass parts.
Then we rehearsed it twice with the music director leading and we were ready to go. It went over flawlessly and (as of yet) I haven't heard of any complaints; granted it has only been one day.
I attended an NO parish years ago that did the Missa de Angelis Gloria acapella. It was the most beautiful part of the Mass and what I looked forward to every week. I am so very grateful that this beautiful piece of music has been restored to our parish. I know that some of you out there hear it every week, and I am aware that the Missa de Angelis has been called the pre-Conciliar "Mass of Creation" (as here) and that there are other settings for the Mass. Fine. But you have to admit it that if you've not had a Latin Gloria in your parish for over thirty years then this one is a pretty good one to start with.
But how about my pastor's explanation of why the Latin Gloria was being used? Most of us who consider ourselves inclined towards traditional things instinctively revert to an argument from the past as to why certain things ought to be done (it's tradition; we've always done it that way; this is what the saints did, etc.); my pastor instead made an appeal to the future: "This is the way the whole Church is going, and you are going to be seeing a lot more of it in the future. This is the mind of the Church and a well-rounded Catholic needs to know these Mass parts." While this argument can't really stand alone, I think it is a very interesting and valuable addition to all of the other arguments (both historical and liturgical) for a liturgical praxis of continuity.
Kudos to my pastor and the music director for getting this done.