Thank you for the explanation, that makes sense. I think I'll steer clear of Android devices then, since there are times when I don't read much and would probably forget to charge it for way too long. As I understand things, it's not good to let the battery go completely empty.
I'll probably visit a store that has Inkpads in stock sometime next week. Hopefully they'll let me open up the packaging and play with one for a bit. If it seems decent I'll buy one.
Thank you for all the help and advice.