As an addendum, I'm not entirely sure you understand what is meant by text rendering since you said levels of grey is irrelevant, when that's arguably one of the most relevant aspects to antialiasing text (unless you have sub-pixel rendering which e-ink does not). The issue isn't the ability to interpret text, but to resolve the edge detail of individual characters. With poor text rendering, your eye can't help but attempt to autofocus something that will never resolve, resulting in fatigue.
(Kindle text rendering problem; source: Wired)
