A 10.3" e-reader in landscape mode is about the size and weight of a paperback book. Is a paperback book uncomfortable to read in bed? Certainly more uncomfortable than a 10.3" e-reader. Honestly, it's a matter of habit. I used to read in bed with a 6" e-reader and now I read in bed with a 10.3" e-reader. And I still read comfortably. And when e-readers didn't exist, I used to read books of different sizes in bed. The "ideal size" is as always a matter of taste and habit. Personally, now that I have a 10.3" e-reader, I wouldn't trade it for a smaller one. Neither for reading in bed, nor for reading anywhere else. I've gotten used to that size and I don't want to go back to a smaller size.
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