Used not to like Gorecki too much. Heard his Harpsichord Concerto as a student and lumped him in the sub Arvo Part minimalist slot, then heard this.... and changed my mind whilst the first chord was sounding. Some music doesn't wait to work its magic.
You get a hint of just how highly charged the first performance must have been.
I think with a little tinkering it would be performable by a church choir, a little discreet doubling here and there. It's just too long to be put in a Mass.
PS If you don't like the audience noise, there's another recording with Harry Christophers and The Sixteen.