Having had the privilege of singing with Shaw on many occasions, I know and honor him as a passionate choral technician and teacher who could always bring out better than the best in an amateur group. Nearly all the choral directors I've ever sung under pull "Shawisms" from their bag of tricks to improve pitch and accuracy. However, in today's era where we can choose from a plethora of professional groups (Montiverdi Singers, Tallis Scholars, Dale Warland Singers, etc.), sadly, Shaw's recordings usually don't compete.
Particularly in his final years when he would hold his Summer Festivals in Southern France (attracting a huge flock of choral directors), the recorded product (released on a series of Telarc recordings) has been consistently mushy and lugubrious - this one in particular! The usually fine Telarc engineers should be ashamed (as well as their marketers who where obviously trying to ride the Shaw band wagon as far as they could)!
The Barber Agnus Dei (for which I've yet to find a satisfying recording) sounds like the singers are submerged in molasses! The tempo is unbelievably slow and there is a total lack of clarity in the inner parts. I recently was driving through Colorado during the NPR fund-raising week and heard a pair of well-meaning NPR announcers slavering over this recording - I thought I was going to puke!
Much better recordings exist of the Gorecki, Pärt and Martin. With due deference to the master, I wouldn't touch this recording with a ten-foot pole. If you simply must purchase Shaw recordings, stick with the larger choral repertoire - you're guaranteed to get good choral singing and excellent soloists (but usually coupled with a less-than-electric performance).