Having had v-brakes with Travel Agents (linked to Campag Ergopower 8 sp) on my tandem, my conclusion has been that v-brakes are total crap (too much looseness in the system, and this is with Shimano v-brakes and Tektro mini-v-brakes), the Travel Agents remove any mechanical advantage v-brakes might give you, and brake adjustment with brifters/no Travel Agents has an extremely narrow/limited scope. I would stick with the cantis and try different pads. V-brakes were designed for mtb's in off-road conditions. They are completely inappropriate on road bikes with road levers.
Respectfully disagree.
My wife's bike mated with Shimano STI shifters and travel agents. No trouble in over 5000 miles on this set up. They even work well with her short reach levers! While I built up her bike from a bare frame, a complete bike can be ordered from the builder with exactly the same set up. They would not risk their reputation putting together "total crap." They have more power than the canti's on my cyclocrosss bike. I am seriously thinking of putting a pair on my Surly LHT touring bike.
Having said that, my cantilever brakes (Cane Creek w/ Kool Stop combination pads, and same brakes as on my LHT below) worked exceptionally well for the "panic stop" station, leaving a nice skid mark when I was going through the bike safety instructor's training exercises in June.
