Using Dura Ace caliper front and Tektro V brake rear with Koolstop Eagle2 brake pads; have replaced the pads ONCE in 30,000 miles on our Zona tandem. Team weight is just under 250 lbs.
Yes, Arizona is hilly/mountainous.
Best brake pads we ever used for rim brakes were Scott/Mathauser (no longer available). Lasted 50,000+ miles.
Rim brakes have proved to be just fine for us. Yes, have have ridden tandem with disc front and rear; considered them overkill for our team.
Have done 11-mile long 6 to 7% grade switchback descent (Kitt Peak) and rims never overheated. Did have to stop half way down as fingers were cramping. Felt rims and they were warm, not hot. Continued descent after a few minutes. BTW those were old fashioned Mafac cantilevers with the S/M pads.
Just ur experience.
Pedal on TWOgether!
Rudy and Kay/zonataqndem