[wtallis]

That eInk-based device you want won't happen until eInk refresh rates improve by a lot - they list an image update time of 120ms for monochrome, and up to 980ms for color. That needs to improve by at least an order of magnitude before it can be considered responsive enough for any direct-manipulation application.

[supar]

In this area was hoping for the NoteSlate to succeed, but it seems that it went waporware.

For notetaking the refresh speed is not so critical, as the areas to refresh are limited to the writing spot. You would probably notice lag, but if you ever drew with heavyweight painting/retouching programs, lag sometimes is introduced by processing and you just get used to it (you just don't expect immediate results and keep going).

I would still prefer a slight lag and the ability to avoid a glass screen in this case.