I´m riding discs now and I know I´m never going with Vs again, their stopping power in rain is unnafected (from my experience), they modulate quite well and they stop superbly, they are great for trials applications, when going downhill, slightly pulling the front brake will immediately control my speed and they do not get my arm tired, they are easy to adjust, their performance is unnafected by the condition of the rim and overall they are just too great for me.
And the funny thing is, I´m not even using high end brakes, just Avid BB5 mechs!, I can´t even imagine what some nice hydro brakes (like Juicy 7s) will feel like.
Go disc!