I have Tektro Oryx canti's and have ZERO problems with them. They stop me as good as my road calipers. I run the Kool-Stop Moutain pads and they were very easy to setup with no squeal and minimal shuddering on my cross bike.
I agree with Stevetone about needing different levers for canti's and vee's. It seems that at least half the time that people jump on a forum to bash something, it turns out to be user error.