Thanks, Jon, for the Nik steer. I've downloaded it and will see what the learning curve is like. Photoshop and InDesign (CS5) still work perfectly well in El Capitan, though.
There is a problem in Photoshop CS5 and both Yosemite and El Cap: If you try to use the eyedropper to select a color for the Color Gradient tool and you click off the image, Photoshop crashes instantly. I've encountered this problem and a lot of other folks have as well. There appears to be no workaround other than to upgrade to CS6 or later.
