Like Tom, in the above video, I enjoy tinkering around, fiddling around with twig stoves. I have two of them - a Solo and a Littlbug. (Yes, the “e” is intentionally omitted.) both stoves are meant for one to two people. Both companies also have slightly larger versions for 3-4 people. In my opinion, both companies produce equipment that is well made of good materials' and well designed to do their jobs. They approach combustion a bit differently, and both have a little rack that holds a pot of water up to allow (1) flame or radiant heat to act on the bottom of the container, and (2) allow unfettered exhaust of the fire.
The formula for combustion hasn’t changed in the 100,000 or so years that we have been playing with fire: fuel, air, heat. I add: keep rain away, just as a precaution. The two companies both do a good job of containing the fire, thus concentrating the heat. It’s up to the fire builder to furnish fuel and heat.
Solo does a more complete job of channelling air to and around the actual combustion chamber. They claim secondary combustion. And color videos seem to support that. I suspect that, if a thermometer was to be inserted into the flames, a Solo stove is capable of a hotter flame. Can’t prove or disprove that.
The littlbug stove is simpler. Weight and cost are about 1/2 of the Solo. Air control of the fire is more up to the camper. I use a stick to scratch a small trench, say, 1 1/2” wide and deep, and about 8”-10” long, and set the assembled Littlbug astride it. Air flow is more than sufficient, longer sticks can be used, and a longer vertical combustion chamber is created.
Solo has a short, complex air flow system; Littlbug has a taller (about twice as tall) chimney. Both do a good job of ensuring full combustion (I’m assuming dry wood here, equal quality wood in both units). Final results are going to be pretty close - a very hot fire and boiling water.
If one stove boiled a pint or a quart of water a minute faster than the other one, what difference does it make? You’re setting in camp, relaxing anyway. What were you going to do during that minute? Maybe, another sip of that beer? Or another puff of that cigar?