hmm... mine was tested on a rolling road, didn't know there was a problem re: the diff. All my vehicles (American) that have had lockers ATB and LSDs have been done on a rolling road.
"He told me that the rolling road testing machine is the judge and jury on the matter regarding brake loads, efficiency and balance. If the discs (rotors?) and pads are knackered but the car passes the rolling road, all he can do is issue an advisory."
If the pads are worn below their minimum or the discs are worn/cracked etc it will fail regardless of brake efficiency .