I'd really like to use this on Amazon books that I've "fixed" - I'm a little anal about metadata and TOC stuff. I did notice up-thread, that there might be a problem if the book exists in the archive - can someone elaborate on that for me, please and thank you?
I think you're always going to have trouble with this if the ebooks already exist in your Kindle archive. There always seems to be some confusion as to what it's syncing to exactly; should I sync to the original version from the archive, or should I sync based on the "fixed" version?
You (or should I say we) need to find out if the new version of calibre is changing the asin field (since it already exists) of your modified Amazon purchases. If it is, I suspect that you should be able to sync (furthest read page only), since it's getting a new, random, different (fake) ASIN number.
If calibre is leaving the existing Amazon ASIN field alone... then you're probably going to have difficulties. In essence, you going to have two different copies of an ebook with the same ASIN (the one on your devices and the one in your archive). In which case, the legit version in your archive is most assuredly going to take precedence.