I can't help on the "medium-duty" part, but my Barth motorhome has HydroBoost hydraulics, and discs at all four corners. The rear axle is a Dana 80, and the hub has to come off to remove the rotors, which is a double pain because I have wet rear bearings.
One thing many med-duty trucks have is stud-piloted wheels, where the studs take the load, as opposed to hub-piloted, where the hub takes the load. The front brakes are easier, since they're on a dry (grease lubricated bearings) hub.
Brakes are Dayco all around.
'94 Barth 28' Breakaway M/H ("StaRV II") diesel pusher: Spartan chassis, aluminum birdcage construction. Peninsular/AMG 6.5L TD (230HP), 18:1, Phazer, non-wastgated turbo, hi-pop injectors, 4L80E (Sun Coast TC & rebuild, M-H Pan), Dana 80 (M-H Cover), Fluidampr, EGT, trans temp, boost gage. Honda EV-4010 gaso genset, furnace, roof air, stove, microwave/convection, 2-dr. 3-way reefer. KVH R5SL Satellite. Cruises 2, sleeps 4, carries 6, and parties 8 (parties 12 - tested).
Stand-ins are an '02 Cadillac Escalade AWD 6.0L and an '06 Toyota Sienna Limited.