When checking the PMDG cockpit options you will notice why there was never any need for an EFB inside a PMDG plane 
Everything is implemented flawless into the FMC and lower EICAS screens. 
There is even a moving map on the extra screens to the left and right side of the cockpit.
The EFB in various payware planes has been established in aircraft without an FMC or MCDU to still be able to easily click through the features and for quick refuel and one click payload options, but this feature has never been necessary in a PMDG.
Still it is of course nice to have because it looks good and adds a nice extra moving map onto the side windows. And maybe some great calculation options to better spread the cargo containers and the fuel balance.