I had a Hurricane system. The newer ones have a larger reservoir which acts as a heat sink and reduces the duty cycle time. For a sailboat, it was a significant amperage draw between the circulation pump, the thermostatic fans, etc-- about 7 amps when running everything. That was a lot of juice. (but I had a catamaran and pushed that water around 100' before it got back to the heater) I got thousands of hours out of it but hated the complexity and reliance on circuit boards, pumps, fans, igniters, burners, etc. The Refleks sounds pretty good to me--it just wouldn't work on a multihull that really needed 3 distinctly separate heating zones.

Going simpler this time around with propane bulkhead heaters in each hull. The downside is carrying enough propane....