Geez, have I been asleep since 2009?? I can't believe I have not weighed in here!
I know there will be dissent - there always is - but there are only two kinds of Wallas owners, those whose Wallas has crapped out, and those whose Wallas is going to crap out. It is jut too complicated and finicky, and when it craps out, it will be at the most inconvenient time in the most inconvenient place, like when you are in Alaska. Ask Bill and El, ask Sam Landsman. Ask us! It is just a matter of time. Happens to some sooner, some later, but it happens to all Wallas owners eventually. Sorry, truth.
We have a Webasto, actually the truck sleeper version, which we bought for about $900, and had installed by Scott Boysen, when C-Dory would still do work like this for C-Dory owners, for another $900, including fabrication of mounting brackets, outside venting, duct installation, wiring, etc. Now you will probably have to find a shop to do it, unless you are pretty good with stuff like this yourself, which I am not, I needed to "call the man"! If you know the Andy Griffith Show you will know what this means, if not, well, you can probably still figure it out!
The Webasto is the cat's meow, highly recommended.