I like it! It looks like it has a lot of potential to be really aggressive. I saw the clip you made of the rain effect you adapted into an engine effect and its going to look good once everything is all said and done. Since you started with the effect in the engine I'd start there. Some emitter nurnies to show where the particles are coming from and then grow from there. But looking at it as a whole it is REALLY hard. Once I started with a tiny spot it grew on its own into something more complex.