I keep seeing people misuse this terminology, so let me try and explain the physics and the history of this term.
Many of the woodgas stoves were based on research done for forced air downdraft gasifiers. It is physically impossible to have a true downdraft gasifier that is naturally convected.
What the original scientists did, is make a naturally convected version of their forced air downdraft gasifier. Because there was no fan, it was really an "updraft" gasifier. I guess in their infinite wisdom, (or as a joke) they called their new design a "reverse downdraft gasifier" which really means, it's an updraft stove, or naturally convected stove.
Just call it a woodgas stove. That's more accurate.
I'd make a few suggestions for an innovative woodgas stove that is light:
1) Only use steel for the inner firebox. If you do not connect the firebox to the outer cover, you won't get heat transfer, and therefore, you can use a light aluminum outer windscreen without the danger of melting.
2) Make your firebox as large as will fit in your pot. You want to be able to load as much fuel as possible to cut down on re-stoking. The heat buildup will also help to encourage total woodgas combustion.
3) Turbulence and heat transfer is the key to efficient woodgas combustion. You want your woodgas to stay in the stove as long as possible so that the combustible materials have time to completely burn. This can be accomplished by using fins to capture heat and introduce turbulence. Think of your outer shell having a cross shaped set of fins inside that the pot will rest on. They not only act as heat "wicks," but help transfer heat to the pot. Do NOT open your pot stand to the open air. You're inviting all your heat and unburned woodgas to blow away in the wind.
4) One of the keys to the Garlington stove, is that the outer shell (not the bigger windscreen) is light aluminum but does not contact the inner steel can. Therefore the aluminum is in no danger of melting. The PROBLEM with the Garlington, is that the outer shell doesn't feed enough air to the primary and secondary sources. (and the firebox has too few holes for efficient air intake)
Try this: Use a LARGE steel firebox so you can load up on fuel. Surround this with an aluminum outer shell stiff enough to hold the weight of a pot full of water. Make sure the outer shell has plenty of big holes near the bottom to feed primary and secondary air, and another row of large holes at the top to vent out the hot combustion gases directly underneath the pot. Enclose the entire structure and the pot with another windscreen made of thin aluminum foil to help protect against wind.