To understand 10-bit color vs 8-bit color, see 30-bit Color Support in OS X El Capitan with Dual NEC Wide Gamut Display + 32-bit Color.
Hooray! After many years, finally here in late 2015, 10-bit color is available on OS X El Capitan, and now Adobe Photoshop CC 2015 supports 10-bit color in the latest update.
In a cruel twist for my work, 10-bit color requires that GPU support be enabled—but enabling GPU support yields blurred images in Fit on Screen mode on a 2560 X 1600 display with most of the image sizes I process. So I either get blurred images with 10-bit color, or sharp images with 8-bit color. Gah!
Alas, GPU support is even buggier now, whether in full screen mode or not. Drawing problems start happening (at some zoom levels, though not all) and these affect all open windows once the problem starts.