A frequent problem I have with Trapcode Particular is the tendency of sprite and poly style particles to 'clip' through one-another, causing a visible pop (or in some cases and annoying continuous flicker if two particles have spawned in the exact same location) as the camera keeps changing its mind about which particle is in front of the other.
This is most annoying when trying to simulate lazily floating smoke or steam, where there's no way to hide the jarring effect of particles suddenly switching places. I've tried everything I can think of to get rid of this, from decreasing the overall number of particles to changing emitter size to trying to expand the z-depth between particles to adjusting the transfer mode to screen, etc. ad infinitum.
With hundreds of particles floating around, it seems there is no way to guarantee that particles will not clip through one another, and all it takes is one pop to ruin the effect. I love how fast Particular is and would love to use it more so I don't have to resort to time-consuming 3d fluid simulations every time I want to add a bit of steam or smoke to a shot, but the particle clip is becoming a real deal-breaker.