“Tonally adventurous” is putting it rather mildly, Daniel. There are many spots in the piece where, for instance, a short passage where a D# makes sense can be followed by another short passage where it makes more sense to call the note E-flat.
As other posters have reminded me, I am aware that a cappella choirs tend to sing pure pitches rather than tempered ones, but since we do live in a pretty much tempered-pitch world, at least when we’re using keyboard and fretted instruments, I’m hoping that some choir, somewhere, will be willing to try this thing on, in spite of its tempered pitch nature.
The piece won first prize in the 1965 National Young Composers Contest (sponsored by the National Federation of Music Clubs) and has never been performed, as the choir they sent it to said it was ‘unperformable.’ I think they were wrong. I think the right choir with the right conductor could do it. I wrote it when I was 25 and I’m now 84, and would like to hear it at least once before I pass on. (The ah sounds that Dorico plays it back with don’t quite do it for me!)