In my experience (and opinion) alcohol stoves do not need to be over-engineered to be efficient and/or work in sub zero temps. I also have found the pressurized stoves like the pepsi-can stove design to be quite inefficient,a PITA to make, and don't work well in cold. The two DIY designs I would recommend are:

Supercat Stove (jim woods design) It is simple, strong, semi-pressurized but very efficient. For warmer temps this stove can hardly be beat.

For colder temps, the Fancee Feest stove (zelph design). Also simple and strong. Uses fiberglass wick so that it will light easily in sub-zero temps. Very efficient as well. This is my goto stove.

While these stoves do not simmer all by themselves, it is easy to get them too. A small strip of beer can aluminum slid up to cover the holes (of the supercat) or wick (of the fanceefeest) will allow them both to simmer.

You cannot go wrong with either of these.