My FeatherFire arrived today so I decided to conduct some tests to compare it to my PocketRocket. I wanted to see which is lighter....the Pocket Rocket or the FeatherFire plus windscreen. The FeatherFire (46g) + Windscreen (33g) weighs virtually the same as my Pocket Rocket (87g) so it all comes down to how much fuel they use and the canister weight. Note that I am using methanol in the FeatherFire, which is about 30% heavier than ethanol to accomplish the same thing.
I started out by doing 2 tests per stove for boiling a pint of 65F water. I did one test at max power and the other at about 2/3 power. The FeatherFire took 6:30 (max power) and 7:15 (2/3 power) in addition to letting the stove warm up for 30 seconds each time. The fuel usage was 18g and 17.3g respectively.
For the Pocket Rocket, the same tests took 2:35 and 2:50 using 6.9g and 5.7g of fuel respectively.
Averaging these tests, we can see that the FeatherFire takes about 6:54 and uses about 17.6g of methanol to boil a pint of water, compared to 2:42 and 6.3g for the Pocket Rocket.
This means that the FeatherFire uses about 11g more fuel per pint, but it also doesn't have the 135g canister weight to deal with. A 135g canister contains 8oz or 227g of fuel. Using the 6.3g/pint figure, one 8oz canister has the potential to boil about 36 pints of water. Since the PocketRocket saves 11g per pint, after 12 pints it would have saved the weight of it's canister and would then become the lightest option. Not bad...
I usually boil 4 pints per day for myself, so the FeatherFire stove would be ahead for weekend trips while the Pocket Rocket would take the lead by day 4. However, I could just bring a 4oz fuel canister with the PR instead of an 8oz one for weekend trips. These 4oz canisters probably weigh about 100g (total guess) and can burn 18 pints, so the Pocket Rocket using one of these would pull even around the 9th pint (100g/11g per pint).
Overall, the FeatherFire is only looking advantageous for short trips or trips where I'm not going to boil too much water. However, the FeatherFire has a few other advantages in that it's nice and quiet and the fuel is dirt cheap. It does take longer to boil but that's not a concern for me.
I think I could greatly improve these results by making a few chances to the FeatherFire's setup. First, I could add a reflector disc to the FeatherFire which supposedly reduces boil times by about 30 seconds and correspondingly would save about 1.5g of fuel per pint. Secondly, I could switch to using ethanol which is about 30% more effective for the weight. Using methanol I would probably have been using 13-14g per pint instead of 17-18g and coupled with a reflector disc, I could probably achieve pints using around 12g of fuel. If I can realize this, it would drop the weight penalty per pint from 11g all the way down to 5.7g (12g - 6.3g).
Under these assumptions, the PocketRocket with an 8oz canister would take 24 Pints (135g / 5.7g) to earn back the weight of it's canister....or twice as long as before. That starts to look pretty appealing for the FeatherFire since rarely do I boil more than 24 pints in one trip. Even camping with my wife, that would take 3-4 days of cooking for the both of us.
Comparing a FeatherFire cranking out 12g pints vs. a PR with a 4oz fuel canister and 6.3 of fuel per pint will be interesting. Lets see....if the canister weighs 100g then it would take 18 pints to save enough fuel to cancel that out. However, a 4oz canister can only burn 18 pints if it takes 6.3g per pint so you never come out ahead with one of these. Plus the average weight per day of your trip is higher since the FeatherFire is down to just 1 oz for the fuel bottle by the end of the trip, whereas you always need to lug the canister along with the PR right until the very end.
Now if I can just start achieving 12g pints with the FeatherFire.....first I need to get some ethanol. Too bad the darn stuff isn't sold in Canada. I need to smuggle some across the border :)