from my experience it doesn't matter whether you are using drag&drop or the sony software. When using sony software it gets slower and slower although indexing is running on my fast pc. I asked sony support about this issue and they told me that the prs is always scanning each document on external devices. They recommend to copy all books to the internal memory. They said "300 books are more than you can read...". Didn't ask them about the 16.000 books on your reader Ad.