I agree, water in the pan will not = more moisture in your food.
I've used the clay saucer and I like it, but I did find that food on the middle grate, just inches or less above the saucer, cooks faster now and I have to be more watchful of the temps at that grate.
With water, you could always count on 10-15 degrees lower temps on the middle grate, now they are equal or even higher than my top grate.
I over-cooked a brisket on the bottom grate the first time I used the clay saucer. The 2 butts up top were fine and went as expected, but the brisket finished at probably the 8 hour mark, and expecting it to go at least 11-12 hours, I didn't get it pulled off until the 9-10 hour mark and it was overcooked. The flat was spongy and falling apart. Yuck.
Next time I will put my maverick smoker probe on the bottom grate. I've used the saucer again, but I've not used it while also using the middle grate again. So I have some more learning and experimenting to do.
Todd