I guess my ref to old schule brakes got a bit lost...
Actually cantilevers and old school centerpulls like weinmanns and mafacs have about the same leverge. The issue with the old (and newer) centerpulls was their spongy feel - due largely to the needed cable bridge (we're talkin 'front', since that's where the serious brakin needs to happen). And also due a bit to the old schooll pads.
Sidepulls and newer road designs have only the housing compression to worry about and were/are more responsive and linear to delicate input. AS racing brakes (which they were designed for) the vast majority of use is for light and even application to modulate speeds, especially when in a close peloton. Centerpulls were always slow to react and much harder to modulate well. The old Campy delta design wasn't any better, was a chunk of hardware, and a pain in the ass to keep adjusted...
Having to haul your butt down from high speed is a much rarer occurrance for a roadie.
And brake fade on really long application on steep, long descents might be the place where improvements would make a real world difference.
I think the v-brake application by Giant is pretty well done and it would be fun to ride it down a long descent to see if it holds more improvements than just the better 'aero'.
The v-brake thing is more similar to regular road brakes, in that the compression factor is similar.