The other Dutilleux piece (in addition to the SQ) I recall fondly is Trois strophes sur le nom Sacher for solo cello, which was on an ECM cello disc as well as the Erato box I have. I think my Erato box is 3 CDs, but it was later reissued as 2.
Strange that I never explored his music more...perhaps when I was in my big "new music" phase I gravitated more toward the French "spectralists" (Murail, Grisey, to a lesser extent Dalbavie), to France-based mavericks like Radulescu and Aperghis, and to Barraqué in the Serialist realm.