Well, I think I've got things just about where I want 'em with aircraft fires. (And I did more work on ground object fires and explosions.) All fire hues are less cartoonishly garish in hue (with formerly uber strong reds and yellows), now looking more toned down and realistic.
For the fuel leak fire that separates from the plane, I got the animated texel to display 'out of sync', by having each instance of the 6 in train to have a different rotation. And I've incorporated an alpha channel texture that has more variety in density. These together give the whole fire some variation in appearance along its length. (Previously all 6 instances had the same rotational orientation, making each look like exact clones.)
In the process I've dscovered an interesting thing about effects using animated texels. The Size parameter in the .mat file, if having two different values for the start and end, does not cause the texel to alter in size over its lifetime. Instead, it appears that the average of the two values is applied to a fixed-size representation. For example, if we set
Size 5 15
The texel will have a fixed size of 10m.