I am having a heck of a time choosing which stove will work best for me. Price is close and not really a factor. I can fit the oslo on my 20" hearth but it does look pretty big for a hearth mount. The 400 fits the hearth nicely but will it put out enough heat for a whole house? This is my dilema. What are the differences in firebox volume between the two? Also, is it possible to burn just a few logs at a time in the Olso and still get some heat out of it? The firebox looks pretty large. Thanks guys. 8