sgt rock, the ion stove guy, mentioned to me recently that he had tried a heine pot and gave up on it as far too inefficient, looking at the results here in this thread, you seem to be confirming his observation.
Using SLX, with a standard ion stove/screen setup, ie, smaller and simpler than a cone, I am now getting fairly standard 11 gm (around 14ml) 2 cup at 70F boils using a roughly 10cm pot, that's a ti tall 900 ml I think. With a wider pot, it gets to a bit over 10 gm (about 13ml) for the boil. My tests have also shown that ti is the most efficient, by a measurable amount, thin stainless second, and aluminum last (but I only had a thick alu pot to test on, but it was wide), but I don't have enough samples and tests to really confirm this as a fact, but I do see logical reasons why this would be the case. These tests were the first time I realized that there is an actual practical reason to go with ti pots beyond the expensive gear benefit.
I will be rechecking the specific gravity number of my fuel at 70F because my tests suggest that is about .75, not the often used .8/.79, but I'm going to confirm it using a real graduated chemistry cylinder to determine the true weight at various temps, per ml.
So weigh the fuel to be sure of the quantity required, then pour that into your measuring cup to see how much at actually is in ml.
Personally I would toss any cooking system that requires 18 gm of alcohol fuel or so to bring 2 cups to a boil, 0.75oz fluid (22.5ml), into my project/test box and consider it interesting as a test but nothing more. 20ml would be my top consumption I'd consider, anything more and the setup is flawed, very hard to know which part is flawed without doing fairly extensive testing of all the variables involved, but with a narrow surface, aluminum, there's just not a lot to catch the flame directly.
Allegedly, slx is about 45/45% ethanol/methanol, give or take, with some other ingredients and water (ethanol from standard commercial sources will always have about 5% water, give or take, which means if it's 50% ethanol, you'll have min 2.5% water. That's if you believe their MSDS. But the heat output seems about right, methanol you'd need about 10% more fuel, ethanol alone, about 10% less, give or take.