I sang this in Gloucester Cathedral in July (writeup to follow) and was asked by the conductor of another choir to say whether I thought it would be viable for one of his cathedral weekends. Here’s the list of minimum requirements I gave, with some specifics omitted. The choir is composed of good sight-singers and meets without prior rehearsal, but music and recordings are supplied to members in advance.
a) an organ capable of doing the work justice (Gloucester’s certainly is)
b) an organist of similar capabilities!
c) 3-4 sopranos who can reliably hit the top C’s in the Hosannas. Strictly speaking these are optional and don’t even appear in the choir scores, but congregations who’ve heard the work will expect them. It’s like interpolated high notes in operatic arias. [I’m told that when Langlais heard about this interpolated note he said that he would have written it himself, but didn’t think choirs would be able to attempt it.] I know of no other work one might sing in a church service which has a top C for the choir trebles/sopranos (as opposed to a soloist).
d) a quorum of singers who have done the work before who can lead their sections. I would say one on each part on each side. This work is hard to learn in advance from a score and a CD for reason e) below.
e) adequately annotated scores. You need a second mortgage to afford a full score, and the ‘choir’ version has no leads or anything else from the organ part in it. I had a hired copy which had some leads pencilled in, which helped a lot with learning.
I did this for the first time at the Musica Deo Sacra week at Tewkesbury this year. In fact we sang it at Bristol on a day out and part of the Tewkesbury congregation followed us there. My recollection was that we spent about 1.5 hours rehearsing it – which was a little on the short side for me as I’d never sen it before, but the piece was amazing.