West Marine Three-speed
Electric heaters, which work off of resistance, are going to be all about the same efficiency-wise.It's the other things - construction, fan design, thermostat, heating elements, noise, etc. that will be what sets one apart from another, and price.We don't liveaboard but living in the Pacific Northwest we use heaters a lot, even in August! We chose a comparatively mid-priced West Marine model (http://www.westmarine.com/webapp/wcs/stores/servlet/ProductDisplay?storeId=10001&langId=-1&catalogId=10001&classNum=743&subdeptNum=379&storeNum=12&productId=10837)for several reasons:1. It's low profile won't tip over (but does take up floor space),2. Three speeds/power settings, 3. Easy to take apart to clean (one needs to vacuum the dust and lint out every so often), and,4. In the lower power settings it is very quiet (the squirrel-cage fan gets faster with increased heat settings but it also gets noisier).Your desired 10 Amp input works out to 1200 Watts which is in the middle of the two highest output settings. When it's freezing and we come aboard I'll often use the forced air heater in combination with the electric heater to quickly get the cabin up to comfort range. Once that's reached the lower settings on our 35-footer is sufficient to maintain cabin temperature.Question: You said you're preparing for some "cold weather cruising" - just wondering, is that in Florida???