There's a long standing debate (goes back years) about whether a idle/off eInk device should have a blank screen, keep displaying the last page, or put up some screen indicating it's off.
The advantage to a blank screen is that you know it's in the off state. The disadvantage is that some feel this is wasting the eInk's ability to maintain a static image without power.
The advantage to displaying the last page is that you can continue reading while the device restarts, although with resume times so fast these days there's not really much benefit. The disadvantage to displaying the last page when it's off is that it's confusing between being off vs hung... etc. Some people would think it's stuck and reset it, instead of turning it back on. Again, this is less of a problem with the DR800 since it basically goes into suspend/resume, not on/off.
Putting up some other screen to indicate the device is off/suspended doesn't really give any functional benefit. The devices that blank the screen already tell you that. Putting up some sort of "screen saver" like the Kindle does is more of a gimmick, than anything else. That's not to say it's bad, just that it doesn't really serve any useful function.
In theory it's possible to modify one of the iRex devices to do that, but as far as I know nobody has.