Regarding heat, both my Mermaids have froze up running in heat mode with sea water in the low 40's. That's about the limit for most all reverse cycle marine units. I also found if I start the unit, let it run about 15min, then turn it off and leave pump on (I added a switch to do this), then restart unit about 15min later, it won't freeze up even down around 40F water temp. The icing seems worse when unit first starts up, this gets you through it. I run a lot in the winter, so have a good amount of experience with these things in heat mode.
Above about 45F water temp, no issue with heat at all.
And these things make real heat. Plenty warm. Not like the "cold draft pump" in my house.
Anyone know if they have a fan speed control option? My 12k in pilothouse works great, but moves a lot of air and flow noise is pretty high at the louver. I'd like to slow the fan on low demand times. I'll check the site.