With your 2-zone Dometic Comfort Control Center (CCC), you join the majority of motor home owners that use the same set-up. In my experience ( I am a Dometic Team 2000 Service Center) they have proven to be the most reliable and easy to service t/stat and HVAC system in the RV industry today.
They have many more functions than just A/C and heat. Motor Homes use this system for a temperature controlled automatic generator start if the power fails and the temps drop below a user determined set point (think pets in the coach on a hot day) so the roof airs will continue to operate.
Also, the CCC will control up to 4 zones of A/C, heat pump, furnace or Aqua-Hot hydronic heating. The system generally runs from the CCC to the lead A/C unit (generally zone 1) and then has a series connection to the other units by 6 conductor data cable (like phone wire but with different plug orientations). Each roof air has a connection for the corresponding heating zone and source.
I agree that the cheap RJ-11 unions can be a problem, but if they are properly installed with strain relief and cabled to the inner roof joists and do not vibrate or move around, they are usually pretty reliable.
Lew Farber...RVIA Certified Master Tech...ABYC Certified Master Marine Electrician
SOLAR TECH ENERGY SYSTEMS, INC.
AM SOLAR ...MAGNUM…VICTRON ENERGY...LITHIUM & LIFELINE BATTERIES…MARINE REFRIGERATION