As a feature, I would love to be able to import master pages and style sheets from other AP files. I'm putting together magazines. A significant amount of content comes to me in PDF format. I have to decide each time whether to create a master template and copy/paste each page out of the PDF file or open/convert the PDF file, then manually copy over the master page and style elements. Neither is an elegant solution.
Even better would be a "merge documents" function. This would allow the separate elements of the magazine to be developed independently, then incorporated into a document at the end.