IMO a stove should be more fuel efficiant than have a fast boil time. I use a cat stove that can boil 2 cups of water with .5 fl oz of HEET, in about 4-5 minutes. This is great because most of the time i use 2 or less cups of water. If i am going to want to keep something boiling longer ill use 1fl oz of fuel.
I am going to try the soda can stove side burner design and see if it can be as efficiant as the cat stove. Oh yeah the cat stove i use is the two can design(one 5oz and 3oz can).
I find that adding a wick helps.