I would think you would be fine but I would suggest you visually check yourself and confirm and measure for a future reference. Check again in a year and see what the difference is. This should give some indication on long they may last.
FWIW I use my exhaust PacBrake whenever I can. I do not leave it on but switch it on as needed. On moderate grades I don't even have to use my brakes and I am descending a steeper grade I will apply hard braking for a short period of time to maintain a safe speed. This helps extend the life of the brakes.
At our old house we had a pretty steep driveway and the brakes would get a real good test every time we took the coach out, it would also wear any rust etc pretty fast as we backed out of the driveway. If the brakes weren't up to par I would know real fast.
I do most of my own maintenance so I do a visual check of the underside of the coach when I lube it, looking for anything out of the ordinary. It gives me a piece of mind knowing that all is good.
2002 Monaco Windsor 38 PKD
2005 Jeep Grand Cherokee w/5.7 Hemi