All of us up here in New York where there is a large number of OWB units can tell you it's not a good idea. Like Rob said, gassification is a must, not really proven in oudoor units yet and you can easily burn up the better part of $20,000 on a professionally installed indoor gassifier unit.
For that money you could install a nice EPA woodstove in the living space for recreation or for when the power goes out, etc. and have a stoker boiler in the basement for serious everyday heating.
On a side note, I'm in the heating business and had a long time customer who purchased an OWB this summer without even asking me for an opinion.(I guess he feels he knows more than a 30 year heating guy) when I found out, I told him to take it back and get a coal stoker. (that wasn't a pleasant conversation) . I ended up doing all the piping, etc. for it. Anyway, I was there the other day on another matter, this thing is just belching smoke, liquid creosote running all over, I just don't understand people. We'll see how long before it springs a leak or the doorframe falls off or whatever common failure these things have.