I have been living with a variation of the RMS all winter in an insulated yurt. See http://sundogecovillage.org/sundogecovillage.org/Projects/Pages/Yurt_Project.html
The heated mass has kept the 300 sq' space at an even 50-55 degrees all winter with inside temps up into the 70's if we burn longer than two hours. The issue for me is that we have not succeeded in getting the stove to draw without the use of an electric fan to pull the smoke and heat through. It burns wood down to fine white ash but smokes more than I would have anticipated at the outside stack. Over all the stove has been reasonably efficient for fuel consumption, considering we are using beetle kill Ponderosa Pine
At first the six inch system extended across the 20' space and back under the stove and out the back. With four elbows in place the distance was over 40'. I recently shortened the system to less than 20' and replaced two 90 degree elbows with a curved plenum box. It improved but did not cure the draw issue.
We were never able to get the down draft system to work in the beginning so we created a wood box that burns the wood horizontally. The two departures on the standard design is the horizontal burn chamber and the below the floor exhaust. The drop from the bottom of the barrel to the horizontal pipe run is about 2.5' then about 6' to the plenum. The whole exhaust system is below the level of the fire box.
I love living with the system and I like the ritual of the twice daily burns. The big problem is that the power goes out on a regular basis here. If the fire is full on, we get smoked out when it does. I am determined to overcome this issue and develop the concept further as we add more experimental structures to Sundog.
My question is, is the low exhaust the issue? Should I abandon the heated floor concept and go with a heated bench that exits the barrel and runs horizontally from the there?