My opinion, for what it's worth, is that V-brakes are better than cantilevers. Here's what it's based on:

There's a local dirt road that goes up to the top of a small pass. It's uphill all the way - a nice, gentle climb, and makes for an excellent day's ride with a nice view at the top. Since it's a steady grade up, that means it's all downhill on the return - almost nothing but coasting. However, since there are many tight, blind, gravel corners, you have to keep your speed down, which means tons of braking.

When I did it on my old Stumpjumper with cantilevers, all that braking was painful. I sometimes had to stop to give my hands a rest from too much squeezing. When I got my newer Rockhopper with V-brakes, this was no longer a problem. The amount of effort was much lower and there was no aching.

Perhaps that's not the most scientific study, but it's good enough for me. I have cantis on my LHT. I'm thinking the next upgrade might be V-brakes.