Honestly I still think it's the wrong tech for this use case. I would much rather see a come back of monochrome transflective displays.
Give me an A3 size, monochrome, 4k resolution, transflective LCD, at 30fps, that I can scroll through text naturally and read with external ambient light. That to me would be the perfect 'reading' 2nd monitor.
See the old 'Pixel Qi' displays as an example of this tech.