Scott, since you are a friend, let me confide in you ?
It has always been my "fantasy" to OWN a De Walt Pressure Washer !
They are "in demand" here in Tampa.
We NEVER see them for sale used.
You are one "lucky man" to have one for sale in your area, LOL
Seriously, RCIA is number 4 Google for roof cleaning search !
It is good that we are educating the public about low pressure roof cleaning, just need to keep on and let them know that you should never use pressure on the shingles.