Well, from my point of view, it's not jets that are the important part, it the definable particle emitter.
The ani's I used for the jets are a disruption, and explosion and one little 128 x 128 'puff' ani I made up, so they are only really just to see what the engine (of the game) is capable of.
My own thoughts are that if you put a tiny little object in a game, with 'thrusters' pointing on 4-6 directions, emitting very large, long lived textures (1 fps ani's?), it would be interesting to see what kind of particle effects you could come up with?
All the emitters are optional, if they are not in the table file, they won't appear in the game, simple as that. I'm not certain how Vanilla FS2 would cope with them being there though.
At the moment, for certain ships, yes those particles are a little too 'Fluffy' for my tastes also (Though I still like the idea of breaking one 'particle' down into multiple ones), but you've seen what was done with the standard effects in Inferno, and that was just using the inventiveness of modders coupled with the standard(ish) game Engine
Edit : Bobboau, is there any chance of LOD settings similar to the explosions for this? That way I think I might be able to come out with a little something interesting