I purchased a pack of smaller Sterno cans for emergency use. Over about a five year period about half of them, six or so, lost their contents through evaporation. These were pristine, unopened cans.

I just go with alcohol now. many of the disadvantages you list for Sterno apply to liquid alcohol, such as the nearly invisible flame. At least the alcohol doesn't seem to evaporate and it is usable in a variety of situations.