Hmmm, interesting sounding indeed. I wouldn't however be so quick as to automatically dismiss targiting sfx. The fighters in starwars certainly have them, and for computer guided weapons such as missiles they would make sense.
Pluss, on targit indicators could be used for targiting weak spots on larger ships ala last star fighter, which would give the game both a tactical and realistic edge.
If you haven't played Jim Kitchin's Puppy 1 arcade plane game, i'd suggest you do.
that is purely arcade style, ie, you here planes, and shoot them down in waves for points, it does however feature a rather nice way of showing vertical location by using the pitch of a wind sound overlaid upon the engine, with a higher pitch indicating a higher elivation.
Thus pitch = hight or depth, left/right sterrio position = horizontal position, and volume = closeness to your ship.
Admittedly puppy 1 isn't quite 3D, sinse you cannot actually turn your plane around, and once an enemy plane goes past you, your dead, but if you introduced some factor, ----- such as a proximity warning for something behind, I don't see why this sort of system wouldn't be workable.
Myself I'd rather have a tactical space fighting game where you have to perform actual missions, and hunt down your enemies, rather than just targit and pump with a single weapon as fast as possible.
With our dreaming and singing, Ceaseless and sorrowless we! The glory about us clinging Of the glorious futures we see,
Our souls with high music ringing; O men! It must ever be
That we dwell in our dreaming and singing, A little apart from ye. (Arthur O'Shaughnessy 1873.)