Low and slow naturally keeps the meat moist and tender.
Also steam from the water boiling off disguises the amount of smoke you are actually producing as well as softens the bark to where it never really develops properly.
At least that was my experience before I quit using water in my pan.
The ECB needs all the help they can get. I have been thinking about purchasing another set of hooks to install another area for sand, but still on the fence about it. Currently my ECB is it's best with all the Mod help.