As far as I know, CC Particle World only uses a floor for bounce. I guess you could make a comp where the floor is turned (well, really the entire comp is turned) to some other angle than level to get one bounce from a flat surface. Maybe combined with a gravity that is at an angle it could work.
Particular (commercial plugin) has it slightly better: It has a floor and a wall surface you can bounce off of. Plus you can freely position those layers at any position and angle and the particles will also fall once they go outside the layer area. So that’s a bit better. I’ve used that to a convincing effect in a number of cases even when the bounce surfaces are not actually flat. You can fool the eye to a degree. And you have the option of using a motion path to fake the bounce as well.
For a physics bounce of any complexity from within After Effects, (commercial) Superluminal Stardust seems to be pretty much the only option currently. Even C4D Lite excludes physics.
Outside of AE, there’s always Blender.
Kalleheikki Kannisto
Senior Graphic Designer