Some of the links on this forum allow SMF, at no cost to you, to earn a small commission when you click through and make a purchase. Let me know if you have any questions about this.
My smoker uses a dedicated water pan the full length of the smoker with a1 inch gap all the way around and a self feeding water tank to regulate the water depth which also ensure a steady temp by replenishing as needed. I feel they use less wood by using more of the heat. similar to a Webber kettle but I've noticed there not a popular build. I believe the only down side to them is after about a 15 hour or so of smoking you have to dump the water and refill. Since the water almost stops boiling due to the oil and fat, also disposing of the water. The plus side is you can do some really nice cooks in shorter times at higher temps with out wrapping and getting great results.
When I first started messing around with smoking I put water in my smokers water pan but lately I have been smoking with the pan full of sand and I just can't tell the difference between the two. I did a few smokes before I got the sand with no water in the pan just using the pan to catch drips and I didn't think that maybe a difference on the product being smoked though it did make the temp harder to control thus the addition of the sand. There's a ton of posts on the forum and the internet in general about water or no water the the opinions very widely, do what makes you happy.
tiggy, if you can fill your water pan from the outside you could also try doing the first half of your smoke dry (slows down cook time for more smoke flavor) and then add water during the 2nd half, e.g. when your meat temperature exceeds 100. The water in the smokey air helps transfer heat to the meat better than dry (if you've ever gotten a steam burn you know what I mean) so you can get through "the stall" and to the dinner table quicker.
If your water pan is developing an "oil slick" you might consider a 2nd pan ABOVE your water pan to catch the oil/meat drippings. If you're short on vertical height, try just a flat plate with a slight tilt such as to drain drippings away from your water pan and into your fire or a separate drip catcher. As long as you still leave a couple inches of clear space over your water pan, you'll have no problem keeping your smoker "moist".