The worst brakes ever made?

A rare find these days, Mafac brakes once graced the machines of Tour de France riders. I would love to know what people think of these brakes however. I have heard stories of Tour riders simply having to call out "Mafac" and people would understand that his brakes had failed - such was the regularity with which Mafacs gave out. But other people rave about the brakes, saying they are light and effective. Perhaps they were all these things, or perhaps it's down to which model you used.

Anyway, these are Mafac "Raid" calipers on a nice old bike I saw in Daikanyama.