I'll build a fancy feast stove too. Easy and cheap.

Really, efficiency isn't important to me all that much other than the fact that I want to be able to boil 1l of water. Some of the stoves simply can't do this due to capacity, efficiency, design, whatever. So long as I can boil 1l of water in my 5" pot, I'm good. I'm never out more than 3-4 days or in very cold weather so alcohol usage isn't much of a concern.