I did this for the first time this spring on my 2011 Pro. I bought it in 2013 as a demo unit from a dealer that used it in their cooking school. They did an extreme cleaning on it before selling it.
I knew that I had probably waited too long to do this level of cleaning, and was expecting there to be a lot of ash. But, I found that it was not too bad at all. There was some ash under the fire pot, but not a lot. I was very impressed with how clean it was underneath, and in the back of the unit.
I need to do this level of cleaning more often going forward, but found that it really wasn't too bad.
Still impressed with this machine!
- Gringo