Seriously Kimmoli, if you achieve some eInk OH that size (the bigger the better for eInk, and if I understand well, this would be the max possible) and if the software side works correctly, then I'll give my kidney for one. Add me to the list of the "Shut up and take my money" already.

Ideal final features would be:

• 1. notifications (like for the OLED);
  
• 2. ability to automatically send to eInk what was displayed on the main screen when you pressed power key to lock it (this will not close applications like the swipe down), this way you can easily chose what to display on eInk while saving power in only one move; let's say that locking the main screen with the swipe down (from homescreen/lockscreen/launcher) would rather trigger the aforementioned "notification" mode, so that both modes can be achieved easily without menus or options;
  # Would only send static display, no videos of course, but that wouldn't be a problem as eInk is not made for dynamic content
  
• 3. ability to automatically display certain files to the eInk (epubs, etc.);
  # Might be useless if the above can be achieved
  
• 4. ability set eInk "dynamic" usage on/off by running the TOHeInk app, i.e., make Sailfish understand that the user is currently using eInk as main display: when on, you can use hardware volume keys to turn pages of the PDF or ePub (or scroll a webpage?) that was displayed fullscreen when you pressed the power key to transfer the display and lock the LCD (see #2 feature).

If all that can be achieved, seriously, this is gonna be in the Top 2 must have OH together with the keyboard. Easily. And the keyboard will not be for everybody anyway (plus the experience will heavily depend on how Sailfish can be adapted with landscape mode, keyboard shortcuts like Ctrl+C, and ability to hide VKB, so a lot of challenges remaining).