it turns into the Mad Hatters tree when you start catering for each type of plugin and it's data.
This depends how generic data would be included. It the Import gives the plugin(s) the option to set generic data for each data type an generic way it would be the responsibility of the plugin to make the decision which data would be attached and where.
I don't talk about new Document Types, i just want to fill a few more fields, like Notes on the User Document ( standard mybb) a few fields which store Information from a few of my plugins ( this are generic fields unique to my installation ).
If it is possible to get this functionality into the Importer without hassel - that would be fine.