The Eleventh Hour?

In my four decades of directing music within the Church I've found that most thriving and viable music "ministries" offer some sort of pre-Midnight Mass performance. The most common is the devotional format of the service of Nine Lessons and Carols, modeled after the classic English order fashioned circa 1880. However, any number of variations on that service, or a simple concert that features prominent large works, or smaller anthems/motets in alternation with congregational carol-singing may even be more common than the Lessons format.
Over the two decades at our current parish, we have offered a separate concert event prior to Christmas that generally consists of a major cantata or large work, sometimes with solos, instrumental chamber works, organ compositions and the like interspersed within that model. We have also had years where the concert did not feature a large work or cantata, but had a thematic concept overarching a number of small choral pieces. Such themes included cultural components, styles and periods, specific composers or arrangers, traditional versus modern eras, etc. For example, in 2010 I programmed a concert featuring the works of American Catholic composers of the Victorian era to compliment the 150th anniversary of our parish's founding. That was a bit of a challenge to find significant counterparts to Peloquin from 1850 besides RoSewig et al, so I also tagged along some villancicos known to the missions in California at the time and a spiritual also sung in the era of the Civil War according to Higginson's bibliography.
This last year we held our seasonal concert early, which featured Vivaldi's GLORIA and the Bach MAGNIFICAT. It was a lovely, greatly attended event done well, but we decided initially not to repeat it in the eleventh hour prior to Midnight Mass for a number of sound reasons. Happily, our choir core has been together for 18 years, so once we were free of rehearsals for the "masterworks" concert we were able to prepare well about eight/nine pieces for the pre-Midnight portion of Christmas Eve.
My question to other choirmasters/directors: when you choose to do a "mixed bag" sort of pre-concert before Mass, whether Lessons-based or not, what criteria do you use, if any, that informs your repertoire choices? Do you place restrictions that are related or overlap from our "Catholic ethos" of chant/polyphony preference (even if carried through genetics to modern composers from Saint-Saens to Allen or McMillan)? Or do you allow some measure of "letting one's hair down" and admit pieces that don't have the catholic pedigree firmly in place? As mentioned, that could be spirituals, or gospel-infused arrangements and pieces (by great arrangers like Hogan, Hayes, Dillworth, Thomas), or other inculturated traditions such as Advent or Nativity villancicos, or carols from Hispanic traditions, Polish traditions and such, or generic but worthy new compositions by lower-tiered composers such as Leavitt, Courtney, Rutter, Chris Rice, Hillsongs or Culbreth ;-)?
I suppose what I'm asking amouts to whether such "devotional" or "inspirational" material that you as choirmaster deems to be worthy of public performance within the confines of your church building ought to be discerned also according to the tenets that we adhere to for actual worship at liturgy?