" Aren't they related more to Allison Transmission, Cummins/Cat or Dynomax rather than specifically Country Coach issues?"
Thw Allison trans is pretty much bullet proof and most problems are related to wiring. Cat and Cummins are their own animal and have proven to be equally reliable. I have had both and I feel that the Cummins is cheaper to maintain and I think that Cummins is also quieter mechanically.
The DynoMax chassis was built in the CC factory so you could probably say the chassis is a CC item. Here again, you don't normally have issues with the chassis. The front and rear clips are made by other companies and were purchased by CC