For Example, our 2009 40' Limited FDQS has AquaHot hydronic heating, with engine preheat mode, PLUS we also have 2 - 15k BTU heat pump systems on the roof. So, duplicate heating systems.
With regards to worth having, I'd say the jury is still out on AquaHot vs. Propane furnace. Although, you'd lose the engine block heating with a furnace. The AquaHot is a bit quieter than a furnace, but requires more maintenance due to the diesel burner. 15k heat pump is a huge advantage, especially with a dark paint coach in the sun.
Scott & Marcia Hicks
2009 Alpine 40' FDQS 425 ISL