Maybe it's unnecessary for this game's scale, but it would be neat if your aircraft RWR had a separate sound for radar Spikes (aka, the radar source is in track/lock state) when you're being actively locked by the radar (this doesn't mean you were shot at, it just means you're being locked - and you're PROBABLY going to be shot at).
May or may not add some 'mind game' elements. If nothing else, it would add extra realism.
Also, variations for each faction's RWR sounds would be cool, and make each faction feel more unique.