Craig, I love it when you occasionally pull your head out of your "Ash Can" and drop in with us ordinary folk on the hearth-related forums. Your experience and viewpoints are always welcome. ;-) What's the financial incentive to do real-world efficiency testing? These studies are rarely funded by the industry. Last thing they want is for folks to find out that half their computed fuel may be going up the chimney. The government(s) paid for a lot of the old studies way back when, and the EPA used the results of these tests to formulate a strategy to reduce emissions into the environment. There is very little work of this kind being done in academia since both funding and interest simply aren't there any more. It would be a pretty expensive study to install flue-analysis equipment in a variety of homes and see how they do in the real world of common users. There have been, however, numerous studies done under controlled conditions in laboratories using cordwood burned in the theoretically most efficient manner inside special calorimeter rooms, and the results were a lot better than 35-45% efficiency. Combustion efficiency in a conventional airtight wood heater a lab setting can be almost 90%, and overall heating efficiency well over 60% in the same stove when using the very best and scientifically sound burn methods. Surely the new stoves have tweaked that by at least a few percentage points, wouldn't you think? But to do that in any stove requires understanding what the most efficient burning conditions really are. The closer you can get your stove to work like it was being tested in a lab, the better the results should be. Either that, or the hundreds of thousands of dollars spent on real-time sensing equipment used at places like OMNI was a total waste of coin. Me... I trust the lab results and try my best to adapt their burning parameters to my home situation. If I got even 75% of the way there, I'd consider it a complete success. Considering that I'm burning about 100 million BTU of wood fiber in a home that theoretically needs 80 million BTU of heat energy to maintain room temps around the clock for the entire heating season, I think I'm doing OK. The extra few percentage points I might get out of the newer technologies hold little interest for me, not as long as nice old VC stoves and such are still available. Now if you can come up with one that takes whole logs, cuts, splits, dries, and feeds them automatically to the fire and leaves nothing but blue skies behind the view of the chimney top... well, I'm all over that one. To me, it's obvious that these new heaters aren't achieving real-world efficiencies even close to the advertised claims just by looking at the wood consumption reports here on the forum. There are folks here burning more wood in a season in their little EPA stoves that I do in my 2.5 cu.ft. pre-EPA stove that's never been rebuilt in the 25 years since it was made. Operator effect is huge with wood stoves, and none of these new marvels are intuitive to run like the old ones. Seems to me that the most efficient use is coming from the same people who successfully burned cleanly and efficiently using the old technologies. In short, long experience, careful observation and a very open mind are needed in all cases to really master the art. The stove itself just ain't gonna do it for ya.