Steve, I just responed to that comment on another thread, not sure if it was you. I do not believe a water pan is necessary in an SI. If it makes folks feel better to do it then they should do it.
I smoke hundreds of pounds of meat in an Ole' Hickory SSG. The SSG is a fine smoker but not as moisture tight as a SI. I have never felt like I should run a water pan in the SSG and no longer do it in the SI at home.