Pots size and windscreen both make a difference.
This is no surprise, and so far I've only trialled the FeatherFire stove with and without caldera cones, so things may change when I get around to testing smaller flame throwers...I'm usung the FeatherFire as a surrogate for the Trangia because they are both open flame, extinguishable stoves that allows me to measure exact fuel consumption by weighing the stove before and after. Starting fuel was always 25g.
1) Foster's can, no windscreen. Boiled 2 cups in 6'30". Used 18 grams of fuel. I did this test twice because the fuel seemed very high, but it came out exactly the same both burns. The flame was reaching almost halfway up the sides of the can by the time it reached full throttle.
2) Foster's can plus caldera cone. Used 16g fuel.
3) AGG 3 cups pan, no windscreen. Boiled in 6'00". Used 14g fuel.
4)Should have been AGG 3cups pot with caldera, but I didn't have a caldera to fit this pot.
5)AGG 2qt pot, no windscreen. Boiled 2 cups in 5'30". Used 13g fuel.
6)AGG 2qt pot plus caldera. Boiled in 7 minutes. Used 10g fuel.
7)AGG 2qt plus caldera, but using 90% methylated spirits (watered down 10%). Exactly the same as burn 6. So with this stove/pot/cone combo, fuel quality made no difference. I know from previous White Box stove experiments that it makes a difference with this stove. I suspect that watering the fuel down may also reduce flame size enough to improve efficiency on smaller diameter pots such as the Foster's.
As you can probably do the maths, the weight savings of using a small diameter pot without a caldera cone will quickly be swamped by the extra fuel you would need to carry. Depends on how long the trip is and how much water you boil, and this is not even taking wind into the equation. I suspect the extra weight of carrying something like the Trangia or FeatherFire will also cancel out over time as you really only need burn exactly the amount of fuel you need for the job, and can completely recover the left overs. The other beauty of these kinds of stoves is the ability to 'over-fuel' them to achieve optimal burning efficiency. Fuel performance drops off when the fuel is either too low or too high. I find around an ounce starting fuel to be about optimal for boiling 2 cups. YMMV