Stuart R, yes, that was an oversight, I'm going to correct the simmer data/comments, and add a table that has repeatable and quantified results, I just didn't get to it, it's not that interesting except in theory to me, I'll also use that data to refine alcohol simmering methods and maybe add that too. I'll use your data as well in that chart.
I picked up a few canister stoves to test on which I will probably sell again once I'm done since I find them aesthetically vile, particularly the non refillable canisters, which to me are as far from what I want backpacking to be for me as I could possibly get. I'll see though, depends, maybe I'll keep one of them just in case forest fires start getting even worse and fire controls more stringent, though personally I don't see any difference in actual fire risk, when used competently, between either system, except that risk of catastrophic failure is obviously far less for an alcohol stove, no valves/connections to fail, though that won't stop people from kicking over their alcohol stove cook sets and starting the next forest fire, just as some people will find a way to make a white gas stove blow up as well. Human ingenuity after all can always find a way...
Like Nick, I do not have the skill set required to make white gas stoves fail, blow up, leak, explode, or whatever else, never seen it, never done it, but I do believe that it can be done since I see people report it being done, for those people I definitely encourage them to use gas canisters no matter what, I'd suggest they also avoid alcohol because those stoves also give a good amount of room for user error and other bad luck things that some people I guess manage to do and others somehow avoid.
The white gas thing however was just a little side track on the entire efficiency question, something I'd not tested or checked for years so I thought it would be fun to revisit that matter. It was actually interesting to do it, particularly using the suggestions of people who use and like them. I will do some updates on the simmering consumption for the various stoves, that will form another table, I didn't have time to do that yet. By posting this data publicly, errors can be pointed out and corrected, until the data is fairly accurate.
The real question was actually gas canister/alcohol initially, not in terms of the mountaineering and off/on/off/on kitchen stove type cooking that gas canisters are good for, but normal backpacking. It's easy to go off on tangents when such questions come up of course, and it was an interesting question for sure.
I had actually believed the stories too about there being a cutoff point in terms of days out/cups boiled where alcohol would start being heavier, but as I found, there is in fact no such cutoff point for an efficient alcohol system. Due to cooking time, there is certainly a pragmatic point where it just takes too long for alcohol of course, 8 cups, for example, would take a long time, not worth it for most people I would guess, and you'd need a pretty big stove to hold the fuel.
I noticed here in a recent thread on narrow beer can pots with caldera cones that showed that the 12 gm per 2 cup boil can be reached even with a fairly inefficient pot, ie, that even using what I would have thought the least efficient setup was able to reach the 12gm point easily, so I would call that number a safe real world number for fuel consumption. White gas was really just looking back for me, out of curiosity, to see how good the systems were, and it turned out, with all the good feedback, particularly from people able to use the systems for years without blowing them up, that it was much better than I had thought, with lots of room for improvement. Roger, too bad you're so into canister gas, think of what a decent machine shop could do with that problem for white gas and for an alcohol stove with a true on/off valve, which would make it fully compliant with all fire danger issues. This thread here actually made me realize how good liquid fuel is re bringing the right amount, always, for any length trip, the same advantage would apply with white gas, and that system can be vastly optimized over what it is now in the market. Maybe your comment that it is a dinosaur system is correct in that sense, though not in the sense that it doesn't work or anything like that.
Re the actual tests, I went back in and weighed the alcohol instead of measuring it, and it turns out that 2 cup boils, raising water temp 140F, that is, took 11 gm with a narrow 10cm pot, and 10.(a bit over 0, which I didn't feel like finding the exact number, it's probably 10.25 or so) with a wide pot, but that's only with a well done system, so it's best to stick with the working 12 gm, which seems to be fully achievable by most efficient systems. I'm picking up a more accurate graduated cylinder measuring device so I can get some data better aligned with reality, I believe though I'm not certain that the specific gravity of denatured alcohol at 70F is closer to 0.75 than 0.79, that's something I'd noted months ago but discounted as measurement error.
And, of course, if you go for most optimized, lightest possible, alcohol setup, then you'd use ethanol, which would drop the per 2 cup boil to about 10gm/9gm. Remember, when comparing systems, it's best to compare a normal system against a normal system, and the best/most efficient against the best most efficient for the varying types.
Roger, I'm well aware of your biases, we all form them based on the style of backpacking we do, our physiology, our marital status, and many other factors, but it's important to remember that fact, ie, that's it's simply personal preference, a bias. When, for example, I used white gas, I had no problems with blowing it up, ie, I didn't, and I had no problems carefully using it in a vestibule, with care, and I understood that you start it once per meal, and worked inside that restriction. These were not difficult things to do.
These threads though would lead me to listen to bob gross over you since he seemed able to run the equipment without issues over years, up to the current time, maybe it's because he doesn't have a room full of stoves, but instead learned how to use the tools he has? I won't speculate, it's fine to have biases however, I am forming a strong bias for alcohol stoves, but I can see myself drifting to actual fire over time too, that just has such an appeal to me, same things, silence, less machinery, simpler, more disconnection from industrial supply chains, etc. You know, nature, and all that stuff. I never felt the need for the on/off/on kitchen stove type approach to cooking in the back country, others like to bring that convenience with them, seems silly to me since my goal is to leave that mindset behind me when backpacking, but each to their own, we all have different motivations.
Ignoring mountaineering, snow camping, and large party cooking, those being not really related to the original topic, the outcomes were interesting however, and surprising at times.
Re cooking times, as sgt rock noted recently, "if you are in such a hurry, why are you walking?". He's got a way with words that guy does.
Here's hoping for happy trails.