I don't usually use water on my pits any more. The only time I do is when cooking a bunch of chicken, like a case or more, and there is too much grease going on. Water, or steam, in the smoker creates a bit different taste, it doesn't produce that real sweet smoke flavor I try for, seems to produce a bit stronger flavor. Seems to change the color some as well, making it more "brown" than amber, and I'm real particular about how my ribs look as well as taste.
My Dad uses water, along with some of my friends, and there is not a darn thing wrong with their BBQ, its just a personal preference in how I like to serve my ribs, that's all.