v-brakes suck in the wet. discs don't. if you're riding in wet/muddy conditions, discs > v-brakes. if you're staying dry and clean, stick with v-brakes.
I've got a friend who endoed on the road due to wet rims. He hit the brakes and nothing happened, so he gave it more power. By then his pads had dried the rims, so suddenly he had a more stopping power than he knew what to do with. Left a nice patch of road rash on his face.