Hi Ddanndt,
given the limitations of the current EPUB standard for math rendering, we aer stuck with pdf and djvu, and I agree with what has been said so far that the perfect academic ebook reader isn't there yet, but there are substitutes there, mainly I would say the Pocketbook 902/903 and the Onyx M90/91.
Both have issues (the pocketbook 903 mainly to do with free-hand annotation still very much less than perfect, the Onyx with serious teething problems, but it has just been launched), but I can definitely work with my PB, and I am quietly hopeful that in a couple more months it will get to do what I need it to do (i.e., free hand annotation on PDF and DJVU, not just epub). But it has buletooth keyboard, for instance (I do not need it, but other users have said it works fine), very reasonable text to speech (especially useful if you are reading texts in other languages), and accommodates many formats.
I am very comfortable reading pdf and djvu files in landscape, which accommodates half a page at a time - and for documents where I prefer to see the whole page at a time I just crop the margins with briss. Of course, what is comfortable for me might not be comfortable for you, and what is a reasonable screen for me (the non pearl vizplex) might not appeal to you. Apparently the new Onyx has a great screen.
Neither the Onyx nor the PB are cheap - but I woudn't consider an Ipad instead as I know from other users that you cannot really work on it, and for "just" reading I know I do want e-ink.
If you are not in a rush, I would lurk in the Pocketbook and Onyx forums to see what the developments are - if I were you I wouldn't decide to take (or not to take) the plunge with a new device after only one hour research on the subject
