This thread got me interested and since I have both devices at home right now, both running KOReader -- I thought a comparison would be nice.
Interested to hear what others think, but in person, I find the contrast difference even more noticeable than these photos.
I tried to keep the settings identical other than sizing the letters to match as best I could on the Nook -- both on Bookerly.
https://imgur.com/a/daGNOh4