The Webasto / Espar type auxiliary heaters work very well with micro processor control, but they draw about 130w when lighting
and about 90w when running, so it is not an insignificant electrical
load. They are also noisier in operation. It is a great solution to prevent things from freezing if you set the thermostat low, since it is basically fully automatic in operation.
I can see that when used in any vehicle that is equipped with an engine that the electrical
load would probably not be an issue (particularly if the vehicle is driven/sailed daily).
I am attracted to the total independence of electrical
power of the natural draft type stove, even if that means that operation is not in any way automated.