It is evident that composers of new settings of the Ordinary of the Mass are also seeing fit to write music for the three acclamations at the Mystery of Faith, as well as for the Alleluia and the final Amen of the Eucharistic Prayer. As regards the former, and leaving the others aside for the time being, it is questionable whether the acclamations of a new Mass setting should ever be used in preference to the Missal chant versions:
It would seem to restrict a priest's choice whether or not to chant the Eucharistic Prayer. As an example of the discordant sound which ensues when a celebrant intones the Mystery of Faith and then the people sing a response otherwise than as appears in the Missal, click here. It is arguable that this extends to the final Amen as well.
And if this is not reason enough, then what about the stated desire of the bishops that a common repertoire of music for the Mass be established throughout the English speaking world? This is a commendable policy, and one which is not furthered by parishes which opt for acclamations from Mass settings which are not necessarily widely known. Would it not be nice if one were to attend Mass in Pittsburgh and Perth and Paisley and Portsmouth and be greeted with a familiar acclamation at the Mystery of Faith, if nothing else? Should composers not just focus on writing music for what are customarily known as the Ordinary parts of the Mass - Kyrie, Gloria, [Creed], Sanctus and Agnus Dei, leaving the other parts which appear on all or most Sundays (Alleluias, Mystery of Faith acclamations and Amens) to be sung according to the new Missal tones or otherwise to traditional chant tones (e.g. the triple Alleluias from the Graduale Simplex)? Rumination necessary.