I've had a wood fire stove in one boat, a Heat Pal in another boat, two bulkhead mounted heaters (both Kerosene), one Webasto hot water heat and two Webasto hot air furnaces. What can I say, I live in the Pacific Northwest where it is always cool and when the admiral wants to stay warm, I get heat for her so that she doesn't give me heat. Okay?
I went from terrible in heat options to top of the line in my boats. Guess I just had to learn. The fireplace was terrible--it smoked and if the wind blew, chase us out of the cabin. It also used up a lot of oxygen (something to consider). The heat Pal (alcohol) produced heat but smelled and drove us out of the cabin too. The Heat Pal also produced a great amount of moister...everything below got damp. They still make them.
We've had two bulkhead mounted kerosene heaters, one British and one Force Ten. The Taylor (British) was mounted low and worked fairly well. The Force Ten worked as well but was mounted higher up and our feet got cold. I tried a fan but needed a bigger one. My wife (the admiral) did not like the bulkhead heaters and said they smelled. I enjoyed them however.
On a boat that we charted to others, we installed a Webasto hydroponic hot water system. Expensive but I could write it off. Radiators in all cabins. No smell. Noisy in the stern where the furnace was. Great heat but you had to bleed the system from time to time, mostly after charterers who didn't know how to use it. Probably the best system that I've had.
My last two systems have been Webasto hot air units, one a 1999 and one a 2009. Both were outstanding. The 1999 unit was Wabasto's mid size unit and heated a H380. Two complaints. Once on, it made a loud sound out the stern which made for unhappy dock mates. But we found out they make a muffler and had that installed and our life was good. The other complaint was who was going to get up in the morning to turn it on. I would fake sleeping and sometimes my wife would get up and do the deed--but sometimes she just nudged me and said, "go turn on the heat."
Presently we have a 2009 Hunter 27 with a 2009 Webasto hot air heat with muffler. It uses very little diesel and has three openings, one in the aft cabin, one in the head (I really like that) and one in the main cabin. Takes about twenty minutes to heat the boat up for me but it is nice! Really nice! So much so that I have been taken to going down to the boat in bad weather, turning on the heat, getting my Kindle out and making me a thermo glass of Viva, Starbucks new instant coffee. Great stuff. Then snuggle up in a bunk in the main cabin and read "Three Men in a Boat," for the nth time. What a way to spend the afternoon.
By the way, you can buy Webasto systems in a box for the DIY folk. They say it is very easy. I think the furling main, the Max prop and the Webasto furnace are all mandatory items on my boats now.
Hope this helps.