sorry, my mistake if I havent made myself clear - my primary purpose was to export the books to a clear (clear to me) directory structure.
Then, I'd make the transfer to my new device (a BOOX device, and from what I heard it should support any generic directory structure).
From bits and pieces gathered around the forums, this is what is working as I like:
1) Preferences > Tweaks > "Control formatting of title and series when used in templates": change it from "save_template_title_series_sorting = 'library_order' " to "save_template_title_series_sorting = 'strictly_alphabetic' "
2)
Code:
{author}{series:|/|}/{series_index:|| -} {pubdate} - {title}
I leave it here hoping it will help others!