Just an update...I finally got around to updating my stove. Found some 16 ga. Nichrome wire on eBay and added a wire grate to the stove. Elevating the fire from the bottom of the inner can did increase the stove's efficiency. I was able to boil 2 cups of water in 5.5 minutes (ideal conditions- 70F, no wind) and keep the grass under the stove from scorching. After building the fire with the initial handful of kindling, I fed it with two good-sized handfuls of pencil to thumb diameter hardwood sticks. Very efficient. Low smoke levels as well.
I used your diagram above as a basis for my re-design. I used the same can as I used last time (an 18.5 oz. Progresso soup can). I cut 3 slots about 1" up from the bottom (between the bottom two 'ribs' in the can). I then drilled four 1/8" holes spaced 1/2" from one another, just above the slot (between the next can 'ribs'). I repeated for three more sets of holes, each group spaced roughly 1" apart. I strung lengths of the fairly easy to work with wire across the holes, interweaving it for stability, cutting it to size and bending the ends down so it would stay in place (a bit tricky). I then drilled the 'ports' along the top of the can- 1/2" diameter, spaced 1" apart, on center 3/4" of an inch from the top lip of the can.
The air flow in my stove only goes one way. It's either going down through the burning wood, out the air slot below the grate, and up between the two walls to be re-ignited after it re-enters the burn chamber through the top ports. Or, according to a several (I suppose reputable) sources who have posted on this site, the air is drawn into the burn chamber from the slot below the grate and rises up through the burning wood, aerating it from underneath, and whatever is burning at the top ports is just heated air.
Whatever the case, the stove weighs right at 6 ounces with pot support, does not scorch the ground below, captures the ash inside the stove, and boils 2 cups of H20 in only about a minute and a half more time than it takes with my Snowpeak Gigapower. I'm pretty satisfied with the results, considering I spent less than $20 on materials, including 10 feet of Nichrome wire.