[chias]

the contrast ratio of a black-and-white e-ink screen is significantly better than the contrast ratio of a color e-eink screen when displaying black and white. It's a very noticeable difference between black-and-white vs dark-grey-on-light-grey. The P2D is much more comfortable to read indoors with the backlight off.

https://i.imgur.com/Z2Yrkl1.jpeg

[apparent]

Your reasoning is correct but Pebbles don't use E Ink screens. That's a specific technology made by a company by the same name.