I take a look at the names of those that have posted that they don't use water (in this thread and others) and I consider their knowledge and experience. I firmly believe that if there was any tangible impovement in the finished product using water, more than a couple of those cooks would say water was better and would never cook with out it. I have cookers with and without water, and I have used the BSKD with and without water, a water pan may simplify fire control, and based on that, I recommend using water to beginners.
I also make try to make sure that they don't have the mistaken idea that it makes the meat moister, as it seems once you get that idea in your head that it's impossible to change no matter how wrong it is or what evidence is presented to the contrary.