Thank you both for your advice. I'll go with ePub.
Is ADE broken in a way that prevents me from:
a) reading ePub files on my Opus (that I've transferred from Linux)
b) converting the file to another format?
I guess I don't get the workflow. I thought I could just provide a key from my device to a book shop and then get an encrypted file back, transfer it to my reader and then start reading. Maybe I should wait for my instructions manual before asking any more questions.
