I realize this is ill-timed, since the Church omits the Gloria during Advent, but perhaps this will be a good setting to think about using when the Gloria returns, especially for Christmas. This is the way the ELHB set the alternate Gloria in excelsis in the back of the hymnal (#568). It is adapted from the Spangenberg Cantional (1545) setting, which is represented in Layriz' Choralbuch (liturgy, part 10). One departure you will note is that the "et in terra" ("and on earth") here begins on A rather than on D. It uses the words of the Common Service, with one exception: In the Domine addresses (line 6), it says "O Lord God, Thou Lamb…" which we are used to singing without "Thou." This could be easily be harmonized by slurring A-G on "God" and omitting "Thou." Another change from the ELHB which might be advisable (and familiar) is to amend the rubric, so that we have the celebrant sing the Gloria in excelsis "Glory be to God…", and the congregation and choir respond beginning with the Laudamus Te, "We praise Thee."