6.1 CoP heat pump sounds great until you're on a boat with a leaky radiator

Panasonic's new CO2 heat pump claims a CoP of 6.1, which is wild on paper. But I've spent enough winters on the water to know that fancy numbers mean nothing when the salt air gets in. Let's see how it holds up after five years of coastal humidity. Still, beats the kerosene heater I'm currently nursing along.