Gent's - I agree, there is no formal definition of map or chart or the method of displaying it (be that on a screen or in paper format). However it does say it must be carried. Thats fine if its a stand alone system and you have made provisions in case it fails. The real issue here is the intergration with GPS and the potential for GPS to not work.
Equally consideration should be given to (the very unlikely) scenario where no electrical devices are working. To me the simple answer is a paper backup. In my own aircraft approach plates are stored in the database (which is frequently updated) however that does not stop me having paper copies and maps (which I print out before the flight) in my flight bag as a backup, in much the same way as I carry a torch for flight at night.