We did not have trouble with our Diesel Particulate Filter/regeneration system in our 2008 Dynasty (drove to almost 70K). Currently at 46,000 miles, no trouble with the DEF system and DPF system on the new coach.
I'm not saying that there cannot be issues but if you are not wanting these systems, those coaches are just getting older and older. That's not a bad thing as motorhomes are not driven enough to be major polluters, it's the OTR trucks. We need to protect our environment, I don't see why people can't see that.
In the 60's and 70's, you couldn't see houses along the interstate in Los Angeles because of the smog. It is amazingly clear now, not perfect but 90% better. To be clear (no pun intended), I didn't see it myself, I'm getting that info from friends who live/lived in that area then as I didn't arrive in California until the early 90's. I see these emission systems as an advantage to our health.
We visited India in '96 and that was a real eye-opener on pollution. :E
I gotta go, there is a tree outside that needs a little hugg'n. :p
Safe travels,
MM.