If we're going to talk about realism, then we should acknowledge that someone who shoots for a living should have some sort of learned skill advantage over someone who fixes things for a living. While I'm against random crits, I'm all for the idea of skills improvements for each level. It's perfectly realistic that a veteran gunner should be able to manage his gun better (+X% accuracy, +Y% turning speed). It's perfectly realistic that a veteran engineer should be able to get more out of his tools (-X% repair cooldown, +Y% damaged repaired per hit). It's perfectly realistic that a veteran pilot should be able to push his ship's capabilities further (+X% horizontal acc., +Y% rotational acc., +Z% vertical acc.).