None of the e-ink devices have a backlight. The Sony 700 had a front-light. If you really want backlight, you'll have to go to the LCD side of things. Not the reflective, but the transparent (or transflective) ones. But the transparent ones are generally not easily readable in bright light, unless you turn up the backlight to the max (which will drain the battery faster).
I personally use two readers, one e-ink for daylight reading, one LCD for nighttime reading.