I’ve recently changed my views on ultra lightweight gas canisters that fit, along with a pocket rocket sized stove, into mugs,and small pans. They’re less economical compared with larger canisters and you end up with a load of three-quarter empty canisters that don’t have enough fuel left inside them to risk taking on an overnighter. Also, you can easily run out of fuel with a full one if it’s providing a couple of meals and several brews for a couple of people. They might come into their own for ultra-lightweight mountain marathons, but even on last years OMM we took a 175g and a 125g canister between us as having plenty to drink and eat was more important to us on the overnight camp than saving a few ounces on the two days running.
A typical 100g canister, such as the one below costs between £2.80 & £3.99. The 175g canister on the right cost me £1.89 at a hardware store (and they’re even cheaper if you buy them in bulk) 275ml beer bottle there purely to illustrate size. I always take whisky on the bivi 😉 ….