"BTW: What about the absence of the fuel tray did you find "unacceptable" with the one you tried?"
One Esbit burner had lost its fuel tray, and I tried to use it. Trying to set up a partial Esbit cube for burning was impossible, because a partial cube tends to be rather rounded. Trying to set an new Esbit cube into vertical position is also impossible. Sometimes, if you have something serious to heat, you can use two cubes vertically. However, I can't see how that would work at all without the fuel tray.
So, eventually I discarded the broken Esbit burner and got a new one just like it with its fuel tray intact, and that is what I continue to use.
I think we are in agreement that it is possible to use one without a fuel tray. My point is that a complete one is better than an incomplete one.
I have a close friend that travels some very long European trails, so I had initially thought of purchasing your product for the friend. Then, after I stared at the photo long enough and I read Ken's remarks, I realized what was there. If I still bought your kit for my friend, I would get it, then pitch the incomplete Esbit burner out and substitute a complete one, then give it. I think the complete ones cost about $15, so I don't know what the incomplete ones go for.