I played around with cascade a little and there was something I really disliked. You either have to start from scratch or you have to copy an existing effect and use it as a base.
I would really like to see a preset system where you could use commom effects such as rain, snow, clouds, beams and explosions etc. as a preset and work from there on. I imagine that would speed up the process going from a new particle to something quite a bit.

In addition to that you could make them sharable. So you could export and import presets shared in the forums.