For me the benefits of discs of better modulation of stopping, better stopping with a load, better all weather stopping outweigh the downsides which as I see it are
extra weight - its a tourer, I dont care about weight
aerodynamic penalty - its a tourer I dont care about aerodynamics
possibility of damage in transit - Im touring in the UK, from either my doorway or somewhere I can get to in a train. If its damaged its my fault!
Lack of spares - Im touring in the UK.
Brake fade - I think is probably a bit of a red herring, especially if you alternate braking down a hill between front and back brakes.
For other people I can see how their results would differ.
It does get rid of one sight benefits of the canti's I currently have though, which squeal like a bugger and very effectively announce my presence to stupid pedestrians who step into the cycle lane...