We weigh in as a +/- 250 lbs duo.
We use a Dura Aca caliper front and Tektro Mini on the rear. 25,000 miles on them so far on this tandem. Work great, stop great, no squeals.
All of our previous custom tandems had rim brakes only.
We do live in hilly terrain (AZ) and have done descents from 9,000+ feet with no stopping issues.
Much depends on your braking skills/confidence.