From the CIRM:

The Acclamation before the Gospel

62. A fter the reading that immediately precedes the Gospel, the Alleluia or another chant laid down by the rubrics is sung, as the liturgical time requires. An acclamation of this kind constitutes a rite or act in itself, by which the gathering of the faithful welcomes and greets the Lord who is about to speak to them in the Gospel and profess their faith by means of the chant. It is sung by everybody, standing, and is led by the choir or a cantor, being repeated as the case requires. The verse, on the other hand, is sung either by the choir or by a cantor.

  a)

The Alleluia is sung in every time of year other than Lent. The verses are taken from the Lectionary or the Graduale.

  b)

During Lent, instead of the Alleluia, the Verse before the Gospel as given in the Lectionary is sung. It is also possible to sing another Psalm or Tract, as found in the Graduale.

63. When there is only one reading before the Gospel:

  a)

during a time of year when the Alleluia is prescribed, either an Alleluia Psalm or the Responsorial Psalm followed by the Alleluia with its verse may be used;

  b)

during a time of year when the Alleluia is not foreseen, either the Psalm and the Verse before the Gospel or the Psalm alone may be used;

  c)

the Alleluia or the Verse before the Gospel, if not sung, may be omitted.

64. The Sequence which, except on Easter Sunday and on Pentecost Day, is optional, is sung before the Alleluia.

From the above extract, it seems clear that the "Gospel Acclamation" is a separate rite or act in itself, presumably not to be omitted (unless proscribed) nor spoken, but sung.

Oops, but omission is only allowed when there is only one reading before the Gospel. So, if there are two readings, it may not be omitted?

An honest and unloaded question:
Owing to its inclusion in The Book of Divine Worship used by Anglican ordinariate Catholics, this makes the Anglican translation of Magnificat therein really Catholic. Does this allow, then, for its use as needed or desired (music-wise) in pure Roman rite situations?
Say, for instance, one were having solemn vespers in English and wanted to use a setting of Magnificat by Tallis or Gibbons etc.? Or, say one wanted to use an English renaissance setting of Gloria or Sanctus at mass (which would be the translation found in the BDW)?

Also, I seem to remember reading quite some years ago that there was actual permission to use translations of the ordinary other than the official ones if one were using an older musical setting that was set to them: is this true or not? (If true, it's certainly a well-kept secret that certain types would hope at all costs remained that way!)

I have also seen metrical adaptations used, but it would seem that unless specific permission is given for them somewhere, they shouldn't be used.

I should hope that the Magnificat (English) from Byrd's Great Service would be permitted at Vespers. It's a stunning work which I've sung many times, as is the Nunc Dimittis for Compline (both are part of the Anglican use Choral Evensong, which merges Vespers and Compline).

Jackson, it makes an interesting point when the translations that are older, but may not be officially approved are clearly better. I think there is a point about what you say in Liturgicum Authenticum perhaps?