There is no doubt that v-brakes are a step above canti's in stopping power, which is why mtb's switched more than a decade ago, until discs became available. The problem is, v-brakes require a lot of cable movement. No doubt that better braking makes you faster, for dirt just as it does for road. That is better stopping power AND modulation of that power. Think about the improvements for road brakes-if it wasn't important, why bother? Cantis are adequate. More important, they represent CX and its traditions. If you keep cantilevers for the panache, better brake pads and adjusting straddle cable length can improve performance.
You know, stopping is good as a last resort, like when you have to make the split-second decision whether to hit the tree or run over the rider who just bit it directly in front of you. I really like the Avids, but you have to go with a wider cable/straddle hanger. Check out the ones from Salsa, and set them up about 1-1.5 inches above the tire. Do that and you're in for a treat. And way cheaper than new brakes.
I can get really good modulation, good stopping/scrubbing, and I can get the wheel off really easily, even with tired/wet/cold hands.
I just switched form TRP CR950's to XTR v-brake with TA.
I am fat, so stopping on a normal canti is well, not as easy as you would think. The V-brakes were an adjustment in braking style for the first ride. They will stop ya big time. Now, as a result i can come into corners or other obstacles at a higher rate of speed, scrub some off and then get moving again. If I get too much mud in the brakes then so be it. This set up allows me to ride more agressivly further into situations. as far as how it looks or if it is not traditional....:) I am not terribly worried. Plus as the weigth of the engine comes down, the bike will get faster, and that is free baby!
FYI Cane Creek are made in the same factory as Avid.
Euro X brakes from TRP offer more mud clearance that your standard Avid/Cane Creek/ XTR brakes. I don't say this because we're TRP sponsored. Frogglegs, Spooky or any other Euro brake design will work great in the mud. Your brake setup really depends on your wheels (training and race wheels) your typical race conditions including the occasional extreme conditions like Kansas.
Whatever setup you go with make sure you use the appropriate pads for your rims for the conditions and setup your brakes so they are symmetrical and their operation is smooth and fluid.
i ran last couple years on my Croll:
XT Low Profile Canits (circa 1996)
Now with the giant TCX added to the stable I'm running what I had in the parts bin:
TCX: '89 Deore cantis (non-low profile) front, '96 XT Cantis rear
Croll: '96 XT Cantis front, 1st gen Tektro mini-Vs rear (until i decide what to do)
considering getting whole new set up on the TCX or just getting a set of BR500s to replace the rear on one of the bikes...