Last night I spent way too much time playing with the variable of 'pot height'. The results are really interesting. I did multiple (2) tests at each height and averaged the results (although both tests were always very close because I've been diligent with controlling the conditions).
The stove is 0.8" tall, so the gap between the stove and pot (which is what I'm really playing with here) is 0.8" less than these absolute pot height figures.
Important: These tests were done with very cold water (40F), 500ml of water (6% more than a pint) and methanol fuel (less hot and energy dense than ethanol), so much better results would be achieved using ethanol and a pint of 60-70F water, which seems to be more of the norm.
We can see that fuel economy improves the lower the pot is inside the cone. Pretty straight forward, but good to confirm with actual tests. This makes sense because more of the pot in inside the warm cone, plus the stove is burning slower (due to having the pot really close) which improves fuel economy. Ultimately you could probably get the pot too close and mess up the combustion so much that it burns poorly and thus fuel use increases.
The boil time results are more interesting. We can see that if the pot is too low (ie. 1.4", or a 0.6" gap) then the stove is really getting stifled and a boil takes forever (~13 min) even if we do get great fuel economy. As you raise the pot up, the boil times get faster since the stove has more room to burn. This is true until you reach the point where performance diminishes because the stove is already burning as hot as it can, and the pot is just getting further away. The fastest boil times occur in the 2.0 - 2.3" pot height range (1.2 - 1.5" gap).
With those results, we can choose a pot height that strikes the right balance between speed and fuel efficiency. There's not much point in going lower than 1.8" (1" gap), because the fuel savings are tiny and the boils get a lot slower. In the context of my cone setup, 1.8" is a good height that's biased a bit more towards fuel economy. Going up to 2.0" shaves a full minute while increasing fuel use by 9%. This is a good option for people who don't mind burning an extra 1.5 grams in exchange for a minute saved. Any pot height that's higher than 2.0 isn't going to be much faster (eventually it gets slower) and it's going to burn a lot more fuel.
So the conclusion is that the reasonable range of pot heights is 1.8 - 2.0", with 1.8" being fuel economy oriented, 2.0" being speed oriented and 1.9" likely being a nice all around compromise with boil times in the 9 min range for this ice cold water.
For comparison, my original ULC cone with the wider 0.9L pot and the Trail Designs 12-10 stove averaged 16.5g of fuel with a 8.25 minute boil time in the same conditions. This is very close to the performance I'd get with a 1.9" pot height. At that height, my setup would probably do 16.4g with a 9 minute boil, which is a wee bit worse overall, but I think most of that is attributable to the narrower pot, which is fundamentally less efficient.
Prior to all the testing last night, I did add 8 holes to the bottom of my cone with a hole punch, as I felt it needed a bit more flow. That had a big positive effect (30 second faster boils using nearly 2g less fuel) and I believe I've pretty much nailed the cone design now, so I doubt I'll make further modifications.
I also trimmed the silicone band is half (again) last night. It's still working great and now weighs just 2.5g. Awesome.
Going forward, I've got the cone design and pot height figured out, so most of the work is done. I'm going to play around with different amounts of water and different water temps to get a better understanding of how the performance will vary. As well, I'm going to get out in the field and do some tests in windier conditions and with cooler ambient air.