If you're looking for propane savings, you'll probably be very disappointed. A catalytic heater MUST have outside ventilation (open windows) in the living space to prevent health problems; and adds moisture to the unit, which can cause condensation problems. The furnaces in a RV are about 60% efficient, but don't need outside ventilation into the space, and are designed to heat the tanks if enclosed.
The only benefit of a catalytic heater I can see would be if you are dry camping and battery consumption is a problem (their quietness would be a nice advantage also).
Regards,
Doug