Okay, so i ran a couple bench top tests in my own house. Water was 75 degrees (room temp for me). Elevation is around 200 feet. Using a Caldera full size aluminum cone, for a SP 600. I used a lexan lid that was clear, so i never had to lift the lid to check if the water was boiling or not. My results after attempting to boil 2 cups of water, with the following amounts of alc.
1/2 ounce alc - Tried 3 times, never boiled. Flame always extinguished around 5mins 30 secs. TrailDesigns claims that 1/2 an ounce should be able to boil 2 cups of water. A kitchen test is probably going to be the most optimal conditions anyones going to get. Not gonna lie, was a lil flustered at this. So shocked, i had to test it 3 times. I'll post a video of this if needed. Anyone out there able to get their sp600 setup to boil 2 cups with 1/2 ounce of alc? Could I have a defective cone?
5/8 ounce- Was having trouble with my timer, so no recorded time, however the stove extinguished right as the water was in the very very very early stages of boiling. I wouldn't trust a boil with this amount of alc, considering that my water will almost never be 75 degrees (water comes from my hydration system, which is usually chilled), nor will conditions ever be as optimal outside
3/4 ounce. - Rolling Boil at 6 mins, stove finally extinguished at 7:34
So in all honesty, I would have preferred the ULC version that stores in the SP600. The weight savings, due to fuel efficiency, I get (which is barely anything) with the full size cone, vs your compact cone, are so negligible, and so easily offset by the weight of the extra caddy that I have to carry to store my cone.
However, was your cone custom built? I don't see them selling the ULC for the sp600. Also, looks like only titanium ULC cones at the moment.
My theory on the .5 ounce advertised boil efficiency, is that this depends largely on what pot you are using. I bet if i had a cone system for an MSR titan kettle (which is wider than my sp600) then maybe I can achieve a 2 cup boil with .5 ounce. Also, my other theory is that if i were using .75 ounces of alc, and were able to extinguish the flame right after the water started boiling, then maybe there might be .25 ounces left unused in the stove. Getting those .25 ounces back into the bottle is another story, and not worth my effort in my opinion