And what about the arrangements that start out pretty straight forward, possibly in unison for the first verse, then suddenly split into 4-part Men or 8-part full choir. That doesn't work so well for a group with only 4 Basses, 1 Tenor, 5 altos, and 2 Sopranos.
Sometimes even with a "bigger" group, or a small group with "bigger" voices, the balance just doesn't work out right. Sure those pieces that are performed so well by the Tabernacle Choir or a fine College Choir seem fun to pull out for a Ward or Stake group. But should you? Really?
And even if some of those good singers say they will come up from the audience just for the performance (because they already know the song or they can sight-read well), they don't really contribute to helping the group be cohesive. Plus, there is merit in having those good singers at rehearsals to help the stalwart singers feel more confident.
My advice is to make sure you have the SUPPORT you need before you choose the music. Once you reasonably can judge your REHEARSAL attendance you can responsibly select music to suit your group.
As an audience member, I would much rather hear a simple hymn or arrangement sung well-blended with the spirit than hear ambitious music done poorly.