Truing the rotors and readjusting the calipers yielded a considerable increase in braking power. I can now use it fairly safely, but there's one detail that's still nagging me: the brakes seem a lot more... spongy, for lack of a better term, than the rim brakes on the other bike. Even if I pull the levers with all my strength, braking doesn't instantly happen at maximum power - it takes a fraction of a second for the brakes to go to full strength.
It this something I should expect of a disc brake system? I was under the impression that, if anything, they should be more instant than rim brakes.