I got confused and thought this was the tubular thread.
I have discs on the MTBs, and the cxes, mostly rim on everything else and tandem is rim front, disc rear.
To the tandem. I put a TRP hybrid on there and it is very smooth. I like PowerCordz vs steel cable feel, but the brake is a good option.
I also went with a 160mm rotor from PowerTap and it had something very big before.
I also have the rotor farther from the seat stays/mount as I am neutrally dished on a narrower hub. Spacing is 145mm wide, too wide IMO, but I bought the bike used.
So anyway...
On hard (HARD) stopping now, there is deformation. Maybe the seat stays flex, maybe as the mounts are farther they flex. That takes the brake out of alignment during braking. Of course rim brakes move too and they will rid up the brake track. But I could always (dry road conditions) stand the tandem on the front wheel with rim brakes before the new ENVE serrated things. I don't much care, as I rarely brake, but if stopping hard were important I'd go back to smooth tubular rims and rim brakes. As is, I very much like the rear disc as a drag brake. When I need to stop fast, I use the front and although not as good as a smooth sided rim, it works.
I don't ride in the rain.