Joined the ranks of Sage owners yesterday.
So far I'm enjoying it. I'd hoped dark mode would be easier on my eyes for night reading, but I'm not sure that it is. I had to go through ALL device fonts to find one that was workable (Amasis), even then, I used advanced settings to take ALL weight off and still had to enlarge font size about 3-4 clicks more than my usual.
So, not counting on it as a major aid to night reading. But if dark mode isn't workable for me, the bit of extra screen contrast is helpful at night. I love the new screen and the snappier performance. Ergonomics are not quite as good as Forma, but Sage is not a problem for me to hold either.
Battery seems not too bad, but then I don't exactly have high expectations. No e-ink reader I've owned has ever lasted more than a week of MY reading habits.
The device in its official light green magnetic sleep cover is absolutely GORGEOUS!