I don't have any of these things, so please keep that in mind as I share my thoughts:
Why would you unload that kind of bread on a digital device that does so little compared to digital devices in basically the same price range that so much more?
Like Gaffer, I use my laptop for any thing like this. I don't read a lot of 'text' books on it, but I do read a lot of digital comics on it. I listen to a lot of audiobooks on my MP3 player. And I buy (and sell!) a lot of used books. And I spend enough of my day looking at glowing rectangles, that the time I spend with a book... I kind of like it to be a 'book', you know?
As much as I don't need an iPad, since I have a smart phone, another MP3 player, and a laptop... I would much sooner buy one of those than a book only device. Actually, I'd just go buy a netbook or a different brand of notebook PC that I can actually run 'real' software on.
That's my 2 cents.