Mark said "I am seriously thinking of getting one."
With my Jetboil PCS, 2 cups water from Sierra stream cold to boiling takes 4 grams fuel. And under 4 minutes from the time I set my pack down. (corrected from my original post of 3 minutes)
Comparison for me doing a 6 night solo trip:
Boil about 6 cups total per day. 2 cups morning (coffee, hot granola), 2-1/2 cups late afternoon (Soup, rehydrate meal), 1-1/2 cup evening (tea).
Simmer for 14 minutes (steam-baked muffin)
I could do with a lot less (or no) cooking, but this system keeps me better hydrated than when I have fewer hot drinks. Then there's the luxury of fresh baked muffins.
Stove/Cup 240 grams
110 grams of fuel
95 gram empty fuel can
=445 grams system
Each boil takes 4 grams fuel x3 = 12 grams/day
Steam baking muffin takes 4 grams fuel
Total 16 grams/day
6 days = 96 grams.
(Hiking JMT in 2008 I ran out of fuel boiling tea the 6th morning with a 100g fuel can, although I had extra muffins and treated neighbors to some water for tea.)
Alcohol system (Caldera Keg- H Kit)
176 grams complete, including keg, cone, stove, fuel bottle.
Per Practical Backpacker interview with Russ Zandbergen, boiling 2 cups typically takes 1/2 oz of alcohol fuel, or about 14 grams.
14 grams x 3 boils/day x 6 days = 252 grams
Steam baking muffin.. I guess another 14 grams x 6 days = 84 grams
336 grams total fuel, plus about 30 grams for a second fuel bottle
Total for Alcohol system
176 g stove kit + 336 g fuel + 30 g bottle = 542 grams
So the Jetboil comes out ~100 grams lighter at the start. At the end though the Caldera system is ~200 g while the Jetboil is still ~350 g. Personally I'd rather have a lighter pack right off a resupply than at the end.
TrailDesigns claims that the cone is close to 2x as efficient as most alcohol systems, meaning that another system might need over 600 g of fuel for my trip.
The convenience for me is great. I usually stop on the trail for breakfast and dinner, then have tea in camp. That means setting up the stove 3x per day which is simple with JB, less so with the cone or other alcohol kits. It takes under 3 minutes from setting my pack down to having two cups of hot water. Of course most people don't stop as many times to cook, and they don't boil as much, so that pushes the equation back.
My family of four went 6 nights last summer with a single 450 gram fuel can, and had about 100 grams left at the end. Boiling for four people with the JB is quick because it only takes about a minute for each cup of water.
Some downsides are the closet full of 1/2 empty canisters, having to carry a second (or larger) can if one isn't quite enough, and the cost. I use up the 1/2 cans on day hikes and for my little lantern.