Let me say something about the sbject...
Characters are useful. Many missions suffer of balance problems and the presence of invincible fighters and/or bombers makes everything better. In normal missions, a high number of wingmen dies(wings Alpha through Delta, 16 spacecraft)and the player's squadron should be disbanded. Characters are also useful when writing messages: Command and warship COs are supposed to be flat characters and can't send messages like "Oh my God, a Shivan Juggernaut! Command has condemned us to death! We'll die!". Warship COs should send messages when they're still alive, so you sometimes have to create alternate messages(message 1 is sent from Y when the X is destroyed and the Y is still intact and message 2 is sent from Command when both X and Y are down).
DySkO cited Steadfast...the 35th Black Eagles is a particular squadron, so it doesn't work as an example. That's the most elite squadron of the GTVA and the death of a pilot is a rare event.
That's what I use for characters:
ship-guardian-threshold with a random value between 5 and 35/40
Double the hitpoint of the characters, so they won't be heavily damaged early in the mission.
ship-subsys-guardian-threshold for engine/engines. This one's is important, because characters survive if hit by powerful weapons but their engines can be disrupted.
Advanced AI. I have created a table with AI levels that go beyond General specifications(the best one is...LieutenantGeneral of course

)and characters are highly skilled. Their meneuvers are good, but they should look even better if you use Joshua's mod.
In Steadfast there also are ENEMY aces to face...but I can't tell you more

Gianluca Murazza...
I know him!

John Luke...Bad Wall?!?