Can you backup your DRM'ed ebooks with Calibre without striping the DRM? If so, I'd like to know how. I own a ton of Kindle ebooks and would be infuriated if Amazon randomly decided to delete them.
If you want to go the dedrm way It has been answered a little further down the thread:
https://news.ycombinator.com/item?id=24272631
Edit: link to the dedrm post.