Have made some more small changes after a discussion with Chris Hall. The main one being the creation of two puremvc actors.
these wrap their own unique instance of the UnifiedLoader class, allowing users to separated their view elements (ie swf, png, jpgs etc) from their data elements (xml, JSON etc).
I have made no attempt to enforce this split, the actors are for all intents and purposes the same, so those who wish to bung all externally loaded items into either one are free to do so.
I am at the moment working on a tutorial for both day to day use of the UnifiedLoader, and one for creating custom clients for new and interesting asset/data types.