2015-10-02 by clay@...
Bill, I upgraded to El Capitan on a laptop that had an existing installation of QTR on it and the printing went off without a hitch. However, when I tried to install a slightly fresher version (2.7.6 instead of 2.7.5) I got a scary message about possibly damaging my system. So I didn't do the upgrade. Because the existing 2.7.5 works just fine, I suspect there is some sort of 'phone home' check that the El Capitan OS is doing to find if QTR is on some Apple sanctioned list. But I don't really know.
All I know is that already existing installations of QTR work just fine on El Capitan.