On my recent project, I bought some avid sd7 v brakes and a lever (lever change is necessary for canti-> vbrake change). Back I left the cantis with the hold pads. I can't even lock up the wheels with them. Not sure yet if I want to buy pads or get some v brakes for the back since I rarely use the back brakes.

I do recommend v brakes, lot easier to set up and use, although at this point I think I have the canti setup steps down decently. Improperly spaced cantis will also negatively affect braking.