I have 4 jetboils and Brunton jetboil knockoff. There's one in each of my families 72 hour kits. I've got he regular cups, the Sumo cup and the 1.5L cooking pot. Like has been said, I only use mine for boiling water. I've tried cooking chili or eggs or even meat in the different attachments but they are all too thin and don't distribute the heat from the small concentrated burner very well.
I do a lot of Freezer bag cooking as well as a ton of Freeze dried meals. One of the easiest things I do with Freezer bags is throw a package of Ramon in a 1 qt bag and put a cup or two of boiling water in it. Let is sit for 5 minutes and pour off what you don't want, add your seasonings and jerky and your done. You can do the same with Angel hair pasta and then mix it into a Mountain House meal to turn a 2 person into a 4 for cheap. I've used the Sumo cup with a Qt bag filled with Chili as a double boiler. When the Chili is warmed you can use the boiling water for your hot beverage of choice or use it with a bag of instant rice to go under the Chili. Use the 1 qt freezer bags for Instant potatoes, Stove top stuffing (you don't really need the butter). Yakisoba instant noodles at like Ramon on Steroids and you can find them on sale for under $.50 each from time to time. I love the efficiency of the Jetboil and have never had an issue with cold or altitude with fuel.