murraypaul, the difference between eInk-based ereaders and tablets is, very simply, this one:
- for ereaders, showing a page of text is very close to being in standby. The only power it requires is that used by the device to be ready to respond to commands.
- for tablets, showing a page of text requires significant power because the backlight needs to be on. And the backlight is one of the subsystems that draw the highest power.
So,
as a reading tool, an ereader is vastly superior to a tablet for battery life. Naturally, if you do other things with it (such as web browsing) things change. But of course for that we have PCs... and tablets :-)
It's like a comparison between sitting on a still (but with engine running) motorbike versus sitting on a still bicycle. Both let you relax your legs, but only one of them requires gas!