I put my new Primus 1.0L eta pot to the test against a regular kitchen pot. Both are heated with a MSR pocket rocket running on almost full can of Primus gas, with 0.5L of tap water. Eta pot also has the Primus clip on windshield, thou the test was conducted indoors (too cold outside for upright canister stove), so it may only function as a poor heat reflector.

Regular stainless kitchen pot came to rolling boil at 2 minutes and 15 seconds, eta pot came to rolling boil at 1 minute and 45 seconds. So in the end that's only 30 seconds of time saved, or around 25% efficiency increase, a far cry from Primus' claim of 50%.

The price of Eta pot is about 60% higher than Primus litech, which is essentially the same stuff without heat fin, and perhaps even closer to eta's efficiency compare with the stainless kitchen pot.

So is it worth it, I don't know, from pure cost saving POV it's going to take a whole lot burn to make up the price difference. But on the other hand you can squeeze a few more boil/meal out of the same fuel canister when there is no spare, and that could come in helpful depends on the situation.