"Does anyone have any experience or data on an optimal height for a Esbit stove?"
I use a titanium wing stove. I've tried some variations. What seems important is that the Esbit cube be insulated away from the cold earth, and that intake air gets to it from slightly below. Those conditions are met in the wing stove, since the Esbit cube is held a fraction of an inch above the earth. I've also built Esbit burners where the cube is held much higher, like 2 inches, and that doesn't seem to accomplish anything. I feel that the major dimension to be concerned with is from the burning cube to the pot bottom, but even that can vary depending on whether you are trying to get fuel efficiency, cooking speed, or whatever.
Many years ago I had a steel wing stove. It was OK, up to a point. The steel center pin rusted out, then the whole thing fell apart. However, titanium doesn't rust.