ATDrake wrote "Apparently Sony keeps the full text of your notes and highlights in an SQL database which you can manage with standard tools?"
Then, I must er, read more and not listen to the salesmen in big box stores. I took my dead Sony back to where I bought it and was told my own data was irretrievable. You mean if I can locate my access code for my Sony account my notes are still there? But how could they even know as I was unable to backup? Doesn't make sense to me. The same thing happened with the Kobo. I have a dead device that cannot be turned on - the salesman at Chapters tells me it is not the cable but the actual device.
I don't want to buy anything until it is possible to easily backup notes, preferably by an auto-backup software with hardware as we use on computers, second preference on one's own computer by an online independent software such as Calibre, and thirdly by the manufacturer itself asa las resort. It appears that none of these exist that are very user-friendly, if they exist at all.