I'm not too bothered about players taking advantage of the F/E ratio by using a fast aircraft to browse off massed bomber or jabo formations. If the raid didn't bring their own fast and high planes as cover, that's their fault. In that situation what you gain from the F/E stat, you lose from the ENY stat and in the case of buffs probably K/T as well. I can see that the change would be bad for people who habitually escort bombers however, maybe they could exclude friendly bombers from it.
The primary purpose of the F/E change is to encourage people to engage while outnumbered, not to determine how "brave" anyone is. If someone is up high in a fast plane harassing a massed jabo raid, that encourages his team mates to come in and engage the raid as well. Few want to be first in to attack a horde, but if there's one or two green there already they may be keener to do so. If the raid's high cover is busy looking over their shoulders at the fast guy and not down at the furball, it encourages combat to begin at lower alts. Currently some score-obsessed players see a bigger red darbar in one place on the map and a bigger green darbar at another place and up at the green. With the F/E mod in place they might think of the red as an opportunity rather than a risk, up a fast plane there and get the combat ball rolling.
The point about a red or green icon appearing just before the kill is not a big deal I think, these things would average out in the end. Adding the average range of green and red icons to the equation would make it fairer if a little more complex.