I've never had an e-reader before and I'm wondering whether I should buy the 16 GB version for 339 or the 64 GB version for 480. What do you think? Another question to better assess the situation: If the 16 GB version is full, can you download your e-books to your PC to make room? And/or is there a place on Amazon where you can see all the e-books you have bought - regardless of whether you bought them on amazon.de, amazon.com or amazon.co.uk?