I think your clear choice ought to be the DR 1000s. About 80% of my total e-book reading is done through the PDF format, and going with anything smaller than my DR's 10" screen seems virtually impossible now that I have it. I simply cannot imagine doing it.
I know that highlighting text is an important feature, and it's one that I would enjoy as well, but being able to write on the screen and have your note stay with the page is equally useful.
Yes, iRex is overseas in Holland, but their main vendor in the US,
www.ereaderoutfitters.com, is in Pleasanton, CA.