I like the thorough step by step troubleshooting info. As he states, there is mis-diagnosis everywhere!!Interesting, but it looked to me like the entire article was mostly about regening the DPF (i.e. getting the accumulated soot to burn off), not so must cleaning out the ash, which is what I've read about being called "cleaning".
Its still probably good, useful information since most prematurely clogged DFPs are more than likely caused by soot accumulation rather than ash accumulation.