Well, I finally broke down and did it. I failed to clean and cover up my WSM after my last use and was rewarded with a bottom section full of water and ash. Since this increased the amount of effort required to get it back into shape, I decided to give it a full blown "lazy" cleaning (it's first in 6 years).
I left all of the hard work to
Simple Green Grill Cleaner and a hose. It removed the layer of grease that seemed to constantly be in my water pan, as well as removed some of the thicker "gunk" from the inside of the middle section. Guess I was tired of leaving a big black grease ring anywhere I set the lid/middle section down so this took care of that.
The good thing is it didn't remove the nice patina of a well used WSM, so I imagine it should still hold temps the way I'd expect. So, if you are looking to clean your WSM up a bit, a can of Simple Green grill cleaner is worth buying

Jamie