Now on a mountain bike they are invaluable, i use one of the best on my MTB but today I realised that I think they could a waste of time on a road bike. attacking a descent on a road ride today and I'm doing 45mph, I see a car so I slow to 30 but I'm on it in no time, the next thing the car stops on the hill. Now admittedly I was getting close, so although she stopped it was more my fault than hers. But anyway I hit the brakes (Ultegra units) and I ain't stopping, all I'm doing is sliding along with the back end coming around on me. I manage to see a gap on her inside and just point for it.
I actually didn't stop until I was past her front door. So if my braking had got the better of my grip with rim brakes, what will disc brakes do. As an experienced Road/mountain biker (trail, XC and downhill), All I can see is less control in emergency situations. Also people wasting money on a new fad.
I think my mountain biking helped me but I did shit myself. It was more instinct than calm control.