New cables and Kool Stop Continentals did NOT make my old 105 or 600 brakes much better. The Tektro nutted version brakes did - period. Wish I could stick my Domane 105s on vintage steel.
If you're barreling down a hill and someone pulls out of their driveway or some oldie makes a left in front of you, you need the stopping power. Once going down a big hill on my Ironman I was squeezing the life out of the 600 brakes for 10 minutes, no thanks.