If by “repertoire selection” you mean the musical styles of hymns/songs rather than psalmody and service music:

Worship IV has 613 hymns. Of these, approximately 80% are organ-based, and 20% are piano/guitar-based.

Gather III has 594 hymns. Of these, approximately 70% are piano/guitar-based titles, and 30% organ-based titles.

The hymn section of CBW III has 395 titles, but this number also includes a selection of psalms and canticles. (The psalms and canticles in both Worship IV and Gather III are in a separate section of the hymnal). I did a quick glance through the hymns in CBW III, and it seems like the actual percentage of organ-based vs. piano/guitar-based titles leans more toward the percentages in Worship IV.

Interesting that this came up. I was thinking of starting a similar conversation. So...

At UST's St Basil's Chapel in Houston we recently replaced (Deo gratias!) Gather with Worship IV. Several months ago the university chaplain said 'we need a new hymnal' and left it entirely up to three of us which it would be. I really plugged the Lumen Christi Hymnal, but the others were reluctant, so, sensing the tenor of things, I heartily recommended Worship IV, and the others came along very nicely. Gather had all of around more or less 100 hymns that I would ever even think about using. Worship has quite a few more, and many good ones. We've had it in the pews for about three weeks, and so far I have introduced Iste confessor, Christe sanctorum, Wareham, Laudate Dominum, and some others, including a new text about Christ our Shepherd which works surprisingly well with St Denio, all of which have been very well responded to. The people at St Basil's sing heartily and don't balk at new hymns when they are thoughtfully introduced. However, in addition to the refreshingly good things there are a surprising number of highly subjective texts which, while sung to genuinely good tunes, are not really appropriate for mass. We think of the texts extolling or centred around 'I', 'me', 'we', and 'us' as being limited to the 'folk', pop, and happy-clappy spectrum, but here we have a very generous smattering of them in what purports to be a proper hymnal, a curious wedding of mediocre to fairly good poetry sung to pretty good 'traditional' tunes. Also disappointing are the numerous hymns which have only a loose theological basis but harp rather self-consciously on familiar social issues of our day. These are no more acceptable when dressed up with regular poetic form and a nice tune than they are when they appear in pop-rock guise. Of course, such issues are of concern (I should hope) to all faithful folk, but singing songs about them is hardly appropriate at the Holy Sacrifice of the Mass - maybe in the parish hall, or prayer meeting, but the mass has its own inviolably God-centred emphasis.

I reviewed WIV as a possible option for a parish recently and was highly disappointed in the content. WIII is still available, and it is head and shoulders above WIV. As the robot on Lost In Space used to say in waving his dangling arms, "Danger! Danger! Alien approaching!"