I was testing some particle thruster stuff for the Media VP and for BSG.
I think I know the reason why nobody uses them (well, SoL does, but only for two special missions).
Right now they work like this:

The start is pretty smooth, but end of the trail splits into multiple small particles. That is because the particles at the end are smaller or weaker, or both.
I'd suggest to add a 'distance spread' value, or something similar.
It should look like this with the right values:

I'm not sure, but I think this is about the particle moving speed.
Maybe the particles could start moving away from the ship fast and stop moving in the end.
Right now they all just stop moving I think...