The point is, the UDS was never meant to use a diffuser or water pan. If you want to go for it, but classically its not used.
A UDS lets the drippings keep the meat moist, instead of a water pan/diffuser. It offers a different flavor, but saying one is better than the other is absurd. Different strokes for different folks.
On top of that if you like the flavor of the WSM and modded a UDS to get closer to that flavor, why not just keep using the WSM?
And the UDS needs to get the grease buildup on it, keeping it clean is counter productive, in my opinion, on the way it is classically used.