Terrible, terrible idea:
- Try turning an iPad round a few times. Because they're thin, they're very unbalanced on that axis and difficult to hold securely using the edges. Lots of risk of dropping the thing.
- How do you stop the screen facing downwards from getting scratched? The only way I can see being successful, is to keep the device permanently in a padded jacket, immediately eliminating any usefulness of having two screens.
- I can't see this costing less than the combined price of an eink reader and tablet, and that combo allows you to hold the two side-by-side to, for example, read a book on the eink screen and look up words/concepts on the 'net using the tablet.