jaggy: here are some photos of how I use the edge (physical configurations) so you can see that an external keyboard really isn't that much of a pain (even on a couch) because the edge can sit in a variety of ways --
http://s816.photobucket.com/albums/z...rah11918/eDGe/
Trust me, I'm a total lounger, and I was worried that I needed a keyboard built in because my laptop is really always on my lap when I'm at home. But, I even made a couch work just fine. And if I'm at a desk, the fact that the keyboard is external isn't a problem at all.
Dr T: the only suggestion I have, and admittedly it's not a great one, is to have a journal open while reading a pdf and make your notes about the pdf in the journal document. I've found myself doing this sometimes not because of zoom but because of not enough space in the margins etc. At least it's only one button press to switch to the open journal document, write your thoughts, then press back to the pdf. Again, not a great suggestion if the notes have to be right on the pdf, but if it's a matter of simply taking notes or recording thoughts, maybe it's enough just to make a mark on the pdf to create an entry in the TOC for reference and have more extensive notes in a corresponding journal?