We had good luck with our coach that had the particulate filter regeneration system. We drove that coach for 7.5 yrs and put almost 70,000 miles on it with no trouble from the engine (Cummins 425 hp).
The particulate filter system would go into a regeneration cycle once about every 8K-10K miles. We were clean burning and we average about 7.7 mpg (40,039 lbs.).
Our new coach has the particulate filter system along with DEF (diesel exhaust fluid). At almost 12,000 miles, we are rolling right along. The system did go through a regeneration at about 11,000 miles. Since we had 3,100 miles on it at delivery, I don't know if it happened before we took delivery or not.
If a person looks at only coaches without the latest emissions, the coach is getting older, there could be many age related issues starting to pop up.
MM.