As a Monk I rarely had to use a potion since he healed pretty damn fast. As WD I have had to use several potions so far. Although I'm killing enemies with ease using a combination moves. I am almost done with chapter 1 and I barely started as WD today. With Monk it took me a couple days to get through chapter 1 and I am playing around the same time if not less then I was as Monk. I am also farming a bit as well I didn't farm with Monk, the point is I am killing enemies so quickly that I am getting done faster.
So overall Monk you will barely have to heal but with WD it's better to keep you distance and use your powers to quickly take out enemies. I think if PVP was up though I would kill WD's with ease with my Monk.
All I would have to do is use powers to stay upclose to the WD and Monk has plenty of those powers!