This is excellent; you intertwine many common chord progressions and motives from eras from the Classical and Baroque with those of seemingly modern music, creating an interesting effect (like a contemporary piece making reference to the times of old while still highlighting the music of now).
To be honest, though, I really prefer the choice of an organ over a string quartet, as it gives, at least in my opinion, the movements a much more emotion, even with such registration, but this may just be me. It is a splendid piece of music, nevertheless, and I am delighted to hear the performance of it (even if it be just an organ performance).
