One of the problems with choosing an eReader for eBooks is that if you change it for another type, you might loose the eBooks.

Google has a solution : keep the book on the web and access it on-line with some synchronization services for reading off-line.

Amazon comes with another solution : write eReading software that works on most of the devices. See here :

Read Anywhere with Amazon's free reading apps.

I find it cool and I will certainly give it a try.