Thank you everyone for the responses. I decided to go with the eBookwise and I'm very happy with the purchase. I'm particularly impressed with the three ways of marking up texts--the highlighter, the pen, and the 'dog-ear' bookmarks. The dog-ear was a particular surprise; I'm currently using this feature to mark where new characters are introduced in novels. It's very handy when trying to keep track of a large cast.
While the screen is far from e-ink (I did see a Sony in Target, and boy, that text does look nice), the experience of reading on an eBookwise is fantastic. The ease of reading and annotating from any position, sitting, standing, or lying, is such a relief after years of fighting the spine (heh, both the book spine and my own). The find word feature is great too, and I can see how the flip-between-books button could be handy in conjunction with a blank 'notes' book.
I imagine that the dictionary would be just as slick as all the other tools, but I somehow managed to delete it from my online bookshelf. Especially irking was the fact that I had just been researching the dictionary feature and knew from this forum that accidental deletion was a danger. When I finally decided I wanted to try the dictionary, I started to download it but suddenly realized that I had better check if I had enough free space left, and thus clicked cancel. I then clicked on the circle next to the dictionary in order to see how much space the dictionary would take up, and next thing I know, it's gone, not stored locally, no longer on my online bookshelf, just gone. <Sigh>. We'll see if tech support can come through; if not, I imagine using the hidden "refurbish" option, and re-registering the device under a new username will bring it back. My only worry is that I don't know if this will delete my library or not.