I am not so sure about disc brakes. I have a couple of disc braked bikes (mtb and tourer) and I really like them. However (other than the mtb) what the disc brakes allow me the most to do is run fatter tires. I know disc brakes are better in the wet etc but I really cant see the point on a Brompton where most simply commute in the city. Also a stronger fork will just make the whole thing heavier and make the ride even worse (maybe as I don't see them using a carbon fork).