Yes, I understand that even if in practice, good caliper brakes like the Ridea for Brompton provide sufficient braking.

The drawback of disc brakes is that they will always increase the weight, to have the real power of disc brakes, hydraulic disc brakes are needed (I have TRP disc on my Ti Birdy, they are lightweight but cannot compete against the cheap Shimano Deore of my Birdy 3) and even higher end, very expensive hydraulic disc brakes, weight more than lightweight rim brakes like the Ridea (and its possible to mount eebrakes that weight less and provide top notch braking).