I'm actually not interested in the screen issues, though they may have a final influence over which I decide on.
I have never owned a Kindle, or a Kobo, so what I am interested in is the software and book management.
1) Do either of them allow sorting by Author, providing a "page" or collection that way?
2) How much font variation is there? or is it restricted to the publisher's choice?
I'm tending to lean toward Kindle at the moment, which will then require the conversion of almost 2000 epubs to .mobi format (not looking forward to it, but at least it doesnt have to be done all at once)
3) How do these two manage books which are not purchased from the dedicated store? Are they "registered" in any way with the respective websites, or ignored.
Still leaning toward Kindle, because of the many free books I have acquired over the past 12 months, some at least of which are DRM protected. Easier to convert the non-protected ones, than to strip protection and then convert.
4) Does anyone think there might be an argument for having both readers? (Seems a bit excessive to me, but then, I am given to excession at times

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Appreciate any suggestions and opinions here