[mdwrigh2]

> At a meta-level, I'm surprised that something with so factual (and testable) an answer can still not be settled.

It is absolutely settled, and has been tested over and over again. Power is roughly proportional to the amount of light emitted[1], so having dark grey is absolutely a power savings over pure white.

Google slides: https://www.theverge.com/2018/11/8/18076502/google-dark-mode... Display energy modeling: https://onlinelibrary.wiley.com/doi/am-pdf/10.1002/stvr.1635

[1]: This isn't totally true mostly because the display is broken into RGB elements emitting light of differing efficiencies and human perception of the brightness of those elements is not identical.