Just a thought. I've heard that Be implemented metadata at the file system level. I believe that NTFS and ext3 both support it as well. (I forget whether is was mentioned specifically in the context of metadata, or that ACLs were implemented in a way sufficiently general to support metadata.) If this is the case, why couldn't the system separate the metadata from ePub and encode it in the file system as part of the file instead of a centralized database? This would allow for enough cross over to hopefully make everyone happy. (Kobo would still use the metadata approach, but at least it would be easier to manage without specialized tools.)

Yet, I know there are issues with this approach. The biggest issue is cross platform support and support from file managers and other such utilities. I lived with the classic Mac OS for long enough to have a love/hate relationship with resource forks. But if the basics are there for the three major platforms (and, by extension, Android and iOS), why shouldn't developers start taking a serious stab at implementing interoperability.

Then again, asking Kobo for a file manager is more realistic than that. Sigh.