You're welcome, M. Wastelander. My greeting and offer were sincere. (I was also kidding with you a bit in terms of the wording.)
The only freezes you're likely to experience are with books that are formatted really badly. In my experience, that problem will repeat itself on whichever reader you try, and the books in question aren't usually obtained commercially.
The battery life on all of the e-ink readers tends to be stellar, and the specs are quite similar, so the user's experience, catalog availability (depending on where you live) and the feel of the hardware are probably the deciding factors. I don't know what Kobo's return policy is like (for hardware), but if it's anything like Amazon's, you shouldn't have any trouble trying out both.
The other issue is the format, of course. Amazon is ubiquitous, and they often have the best prices and selection, but mobi is their format, whereas the Kobo uses epub, which is more universal and which I myself prefer. Additionally, the newer version of mobi (format 8) is said to be a lot harder to crack, and I don't like the idea of not being able to read the books I buy on any reader I choose.
One disadvantage to the Kobo can be pricing, since Amazon regularly beats the ventricles out of other stores with its carefully finessed pricing edge. But Kobo has been known to have some excellent sales (though I'm waiting for them to have one on the sorts of books I actually buy).
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Which brings me to people's comments on
Infinite Jest. I've been deliberating about whether or not to buy the Kindle
(or ePub) edition of Raymond Roussel's
New Impressions of Africa because I have a hard time believing anyone went to the trouble to format it to be read idiomatically.
This particular book is an endless epic poem which is made up entirely of parentheses interrupted by other parentheses. Additionally, the book is bilingual.
In a physical copy, the reader who wants to understand each sentence sans interruptions would use post-its to mark the places where the parens resume. I can see the person who formatted the book taking the trouble to do the footnotes and ToC correctly. I can even see them linking open parens (though I doubt they did). But I can't imagine they linked the last word of each interrupted sentence to its ultimate continuation.
The problem with banging out e-book editions of paper-idiomatic books is that the elegant transposition required to make the e-book enjoyable will likely be glossed over, putting the book in danger of becoming unreadable in its new medium.
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One question: Does the Kobo allow for the switching of multiple inline dictionaries the way that Sony readers do? If so, that's an advantage. I've had to convert several of my mobi books to epub just to read them on my Sony readers and take advantage of that feature.