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I'm going to reenter the discussion as I think we are being referenced here numerous times. We climbed and descended Mt Venteux with about 15 other tandems on a Santana tour a number of years ago. Every tandem had brake issues on the descent except the two that had drum drag brakes. We and our travel friends had avid BB7 rear discs and caliper front on our Calfee's and both melted the adjuster plastics off the BB7 caliper. Our friends are from Breckenridge Colorado and are crazy fast descenders but are a light team (280) and very experienced We are heavier at about 340 and lots of miles also. We did not descent with our normal technique but followed Bill McCready's recommendation to use one brake until it fails and then use the other brake to stop and let things cool. Never again will I use this technique. His reasoning is the most brake failures on cars, truck, motorcycles is the process of off-gassing which actually prevents the pads and rotors from contacting and will work again after cooling. However the bike brakes, one don't have enough power to actually allow this to happen and, two parts melt. BTW no one had hydraulic brakes at this time on their tandems. One team with two captains had calipers front and rear and used four water bottles and sprayed the rims all the way down. The stoker was petrified. Fast forward a couple of years we rode TRP HYRd on the rear with a Ice tech rotor and on an unnamed European descent of 17% two teams including us melted the rotors with the aluminum melting out of the sandwich construction. I favored the rear brake but used both and not as a drag brake. Changed my rotor to a Hope V2 floating and completed the rest of the tour. I vowed at that time never to use those rotors but have since changed my mind. Colotandem also melted a rotor on Venteux on a different tour I believe ( another very light team). Fast forward a couple of years and we were early adopters of the Di2 hydraulic brakes on the rear of our tandem with the same Hope rotor and and had good results. We then had a frame issue that may have been a result of the power of these brakes and which lead to a frame redesign by Calfee to accommodate these brakes. We had a new frame built with a disc compatible fork and now have a discs on front and rear with Di2 hydraulic R785 brakes. This has been a game changer for us and have done lots of the long steep descents with much more confidence. We are now using the complete system including the calipers with ceramic pistons and finned pads and the ice tech rotors for heat management. Using good brake technique is at least half the equation. We just completed a self supported tour of Vermont that has some rather impressive descents as we went to many of the ski areas. Our Calfee Adventure tandem is equipped with the shimano hydraulic system and we were very heavy with all the gear (over 400). We had to stop one time to let brakes cool just to be safe but again confident in the system . Our indicator to stop is the brakes get very noisy and start to chatter so we stop. The rotors are a bit noisy for while until they completely cool then are quiet again. We have been thru all the brake systems but am now settled on hydraulic at this point. On our adventure tandem I have two bar systems depending on the terrain we are riding and the flat bar setup has Shimano Saint 4 piston ceramic calipers and they are very impressive and have even better heat management. One team's experience but lots of real world testing and your results may vary. We also have hydraulics on our full suspension mountain tandems with zero issues.