If it is the Sanctus from the Mass of a Joyful Heart I just heard on YouTube, you are attempting to put lipstick on a pig. I wouldn't knock myself out over this one. It's not worth it. It is going to sound like hell with or without you.

I don't know if it's the case with this particular Mass, but often in contemporary music the score is just a transcription of the more improvisatory and free style that the songwriter sings. This frequently results in difficult-to-read syncopation, or the impossible-to-perform sixteenth notes in "Be Not Afraid." If it's part of the style, so be it. That would be like a pianist insisting on playing even eights when playing the boogie-woogie (or a harpsichordist when playing the "notes inégales" of the French baroque).

Oh... and while I wouldn't be too picky about how the choir performs that Mass, I would be particular with the word "timing." Unless you're performing some modern work that requires using a stopwatch for 20 seconds of this, and then 5 seconds of that, we should be speaking of "rhythm," which has to do the the proportional relationships between notes, and not of an absolute duration. A lot of newbie choir singers (especially those with a dance background) try to memorize the "timing" of a note in rehearsal, and then are confused in performance when the piece is done in a faster or slower tempo. Having an understanding of the difference between beat and rhythm, rhythm and tempo, etc. is essential for performing choral music.

@Adam Wood They don't really understand a conductor, and it is piano with a brutally hard acc, so I don't know how I could possibly conduct them. Also I have been told not to...

Thanks for the tips.

I find that they can be a bit over-reliant on the CD, and the CD doesn't necessarily show them how I want them to sing it (and the other pianist).

I had to do some folksy stuff once, a long time ago. I don't know by what experience I knew this, but I knew that the, shall we say, 'period (and genre) correct' way of performing these pieces was, as incantu so well illustrates, not exactly 'as written', but incorpoarated considerable liberties with rhythm and timing. Not really being able to do the music this way with 'personal authenticity', I straightened out the rhythm and interpreted it with the same phrasing and attention to time that I would use in a motet by Byrd or Poulenc, made some adjustments to the accompaniment and played in on the organ. Having done this 'to it' was, to my mind, a very great improvement. And, the choir were very pleased and said 'this is nice! we didn't know it could sound like this! you took the "country" out of it'. Needless to say, I was pleased with myself.

I don't know if it's the case with this particular Mass, but often in contemporary music the score is just a transcription of the more improvisatory and free style that the songwriter sings.

This is true with various traditional music genres as well: the dots are simply an approximation, and the actual rhythm needs to be appreciated by "catching" the music from another musician, not blindly reading it from the page.

And I've also had a classically trained national orchestra member say the same to me about all music: the score is just a guide, a musician must bring both skill and knowledge of the genre to playing it - otherwise it just sounds wooden, like a MIDI file.