Unless they have some wizz-bang new tech that no one else is using yet, which they would shout about if they were, with eInk you can pretty much say “if your use case makes you care much about refresh rates then eInk isn't a good choice for you ATM”.

I agree, but even among e-ink displays there are refresh rates that make it difficult to enter text or view terminal output.

In text editing, I even set refresh in batched bursts of max 500ms (a few chars per display update), to be battery conservative. No problem.