I have a Xerox Workcentre 7225i and it is connected to my wireles network via the Xerox USB Wireless Adapter(497K11500)
I am able to wirelessly print from my computers to this device with no issues.
I have downloaded the Mopria Print Service app (https://play.google.com/store/apps/details?id=org.mopria.printplugin)
and have installed it on my Motorola Droid Android Phone running Android 6.0
If Xerox Standard Accounting/XSA is turned off, I am able to print successfuly.
If Xerox Standard Accounting/XSA is turned on, I am not able to print successfuly.
I have created 2 users within the Xerox WC 7225i. (1111 for black/white, 2222 for color)
The Mopria Print Service app does have a section for authentication where I can enter my account number,
but it still does not work.
Xerox has not implemented Accounting in the Xerox Print Service plugin for MOPRIA, so it would appear they have not figured out yet how to make it work via XSA.
Until it gets SPAR'd (Reported as broken) or FER'd (Requested to be added to its features) then you would need to continue with IPP exception mode.
I do not currently have the ability to test the feature in-house, so I am just assuming it doesn't work and have not by any means verified it in the Xerox test lab.