My $0.02
It is my understanding that the V-Brake requires more cable pull because on a canti pulling 10mm of cable pulls both arms equally, 10mm on each side of the straddle wire, because they are yoked together.
On a V-Brake the cable has to pull one arm, and the outer pushes the other. This means that 10mm of cable pull moves each arm 5mm.
The greater mechanical advantage required of this means that the pivot point of the lever has to be sited nearer the bar.
I have used canti levers on V-Brakes but was never happy with the feel, though they were powerful!
The Shimano SLR system for canti's (as used on all rapidfire lever combos) has a moving mount for the barrel end of the wire. The pivot starts off a long way from the barrel (bringing the pads onto the rim quickly) and as the lever progresses the barrel gets closer to the pivot giving more power and modulation. This also makes them sort of useable with V-Brakes, but only, as said before, on super true wheels.