E-Ink display and refresh rates --- a technical demonstration
Getting a realistic impressing of e-ink display capabilities is difficult, and many product-review videos don't focus on showing the device in operation, especially in comparison with other e-ink displays.
This video is a good overview of display rates and characteristics of a number of bare displays --- these aren't finished consumer products, but the displays which might go into those, or on electronic signage or display systems.
They range from small and slow to larger and high-speed. The displays typical of current-generation e-book readers start at about 8:10, and there's a timestamped index to displays demonstrated in the show notes.
As someone who'se been using (and greatly appreciating) an Onyx BOOX device for much of the past year, this is a useful overview and perspective.
It's even possible to watch video (in black and white in most cases) on newer e-ink devices. I can confirm the results are largely as viewed in these videos:
Have You Ever Seen an E Ink Display Update This Quickly?
https://yewtu.be/watch?v=KdrMjnYAap4