We have a Webasto heater that was installed when we bought our boat. We absolutely love it! However, the greatest benefits are closest to the heater. It's installed up against the transom in our aft berth. The after berth is great, the head and main salon (about equal distances forward) are much more comfortable when it's cool outside, the v-berth all the way up front is still quite cool. We're a little constricted by our battery capacity, so we don't run the blower at full power, and maybe that would make a difference (move more air, and close off the vents closest to the heater). But, I also wonder if installing the heater farther forward would have helped up in the v-berth. At the very least, do everything you can to minimize or completely eliminate the size and the number of bends in the air duct that carries the heat forward.