Comment by subaquamille

Consider also batterie life and how it's affected by load cycle numbers: ablets get charged one every second day and e-ink devices once a month. Consider also technologie obsolecsence: estimate the times it will take in 10 years for your devices to open a book, change pages, mark highlights. I hardly open a pdf now on my iPad mini and my e-ink device from the same period seems to do the same operation at lighting speed.