I'm pretty convinced of them; as I think has been pointed out, Schütz had already written a German Requiem of his own. Don't know if I'd have done any better at illustrating them in concert though. I shall dig around a bit.

There is indeed a Gardiner recording with the ORR and Monteverdi Choir of that very work. (Soloists Charlotte Margiono and Rodney Gilfry.) It's been around for a while - I don't know how exactly it might compare with the performance you heard!

IMO Brahms' "Ein Deutsche Requiem" is a great and fine work of music. I don't find any need to know the text: a work of music should be appreciated as just that: the text is there to inspire the composer who then (if he knows his job - so many don't, but Brahms did) provides music which reaches out to the heart. It's an emotional experience, basically, and with music you don't really need words for that. I dare say if you got hold of the text and read it aloud as a poem it would be boring and not worth the candle. I used to be a great fan of Brahms' orchestral works, and also the piano solo pieces, and some of the chamber music. But I can never quite reconcile his huge reputation with what he actually does when you compare it with his contemporaries, and what greatness they achieved (Bruckner, Wagner, Mahler). But for me the Requiem does not come within those strictures - it is truly a superb work. The big fugues are surely exciting. I did sing in the Requiem as a student, so perhaps the immediacy of thate musical experience then has led me to over-value the work.

Indeedy-doodly - but I don't hear any of Schutz's idiomatic choral writing (antiphonal sections, alternating homophony with polyphony, use of extreme bass tessitura, extended male-voice sections divided into up to 8 parts etc) in Brahms's work?  I feel that if there are links and influences, then they are more textual and liturgical than specifically musical?   Perhaps I am just being too literal about this, and wanting to hear "some moments that sound like Schutz" in the Requiem?