I suppose I didn't imagine any of that being necessary! But I can see how it would be helpful. There's some challenges, e.g. do we treat attachments the same as other items or do they become WordPress attachments somehow? Would there be multiple Custom Post Types? But it might be better in the end to go in that direction.
I don't plan on making any major changes to Zotpress in the short term, but this may be the best way to go in the long term.