For me, it's all about the cost. At the moment, I get all my wood for FREE. So to change to a gov approved source of fuel will cost about £150 quid a month (estimated at the moment). That might be almost the same as having the central heating on. I will need to see this working to know.
If cost is not an issue, MP's etc, then fitting the correct stove and using approved fuel is a NON issue.
A narrow boat on the other hand has other more difficult problems. Defra approved stove on a boat???. Anyway, at the moment it's the house that's in the firing line