[Cerio]

Why would you want to organize your pdfs in folders and subfolders within MS? The point of using a database program like Mobilesheets is being able to organize and search your data in a much more  powerful andflexible way, and being able to find the data you're looking for much faster.

As long as you organize your pdf collection well in the database, I wouldn't care at all about how these files are stored by the program.