As you say, the eReader DRM is not device specific at all, except that you need reader software from eReader (and they are actively developing versions for new device types). The DRM has also been circumvented, so you can even run on devices without eReader software if you strip the DRM.
There are currently no EInk devices with eReader support, but Astak has announced support will be available on all their readers this summer. They will also support Adobe PDF/ePub on the same devices, see
Adobe Digital Editions for EZ Reader. The only current Astak device is the EZ Reader (Hanlin V3), which is on sale this weekend (
FRY's Electronics Astak EZ Reader Blow-Out). Or you could wait for the 5" EZ Reader Pocket Pro (Hanlin V5), or Astak's Mentor line which will be based on Netronix devices.
EDIT: The eReader SDK that Astak is using is from eReader (i.e. from Fictionwise, which is now part of Barnes and Noble). They presumably have their own plans for EInk devices.