There are no ereaders that handle PDFs in the manner you seek. The 900 won't work because of screen size and the zoom needs to be reset with each page turn. The IREX doesn't have zoom, note taking or annotation (as of today). The Kindle doesn't have zoom and the note taking and annotation are cumbersome.
The Entourage eDGe is the best device out now for PDFs including annotation and note taking. It doesn't sound like the form factor will work for you. You may have to splurge on the QUE or keep waiting like many of us here.

The Skiff is due for release this year. Perhaps it will be priced less than the QUE since the iPad is on the scene now.