Alternative to wood for a RMH

Has anyone ever built a RMH that was designed to be fueled with a propane-powered salamander?

If that is a really dumb question, I apologize.  One of the principles I think I may have grasped is that convection is a poor way to heat, whereas conduction and radiation are more efficient.  Also, I know one of the ideas behind the rocket stove and RMH designs is to use the most amazing renewable fuel of all...wood!  However, I think a lot of the design efficiencies engineered into the mass heaters I've seen on this site would be just as useful with other fuel sources.  If that is simply not true, please educate me on why something other than really dry wood isn't a good fuel source for a rocket stove or heater.

Thanks in advance!

Jason

The cost of propane, plus the safety factor of open flame makes a salamander not a very good idea.  coal has been used, some try used motor oil, pellets have been tried, sawdust, wood chips ,animal dung, presto logs, Really nothing is going to be as cheap or as efficient as good old dry cord wood.    

A salamander in particular is designed to run hot and fast, but a propane burner can reliably run at whatever output is desired with no loss in efficiency. So I don't see an advantage to expending the resources (time, space and money) to build a propane RMH.
A wood fire must run full out for best efficiency, so mass is critical for spreading it out.

So, I understand that one of the advantages of the biomass typically used in a RMH (wood) is free, or very low cost.  I agree that having to buy propane would make a low-cost solution more expensive.  I am not advocating this, I'm really asking for a friend.  

I also am led to believe that the mass, in a rocket mass heater, makes for a more efficient heating method.  Instead of forcing hot air into/around a room with convection (boo), the various masonry/RMH heaters rely on the dual concept of heating a large mass to an elevated (yet safe) temperature, and then having that heat radiate or conduct (butts needing warming go 'here') directly to warm us up.  I get all of that and I agree with it.  I'm actually pretty excited about it and definitely aspire to build a wood-fired "mass" heater of some kind, in the future.

I'm willing to stipulate that a propane-fueled supply of heat is not optimum, but what I'm asking is whether or not it could still be used to warm up a mass that is intended to heat a space.  This could be a relatively simple riser/barrel/bell arrangement, for quick heat to a room or workshop, or it could be a much larger cob or masonry mass.  I guess I'm not really asking if this "could" be done, because there is no clear reason why it would fail.  I'm asking if anyone has ever used some kind of gas-fired heating implement as the fuel for a RMH.

If the answer to that is "no", that's fine.  I'm just thinking it might be a convenient (if expensive and inefficient and less sustainable) means of warming up the mass...that heats up the room.  That's all.