Both Newt and LittleStain are two of the most helpful people you will find on any forum. They both know a heck of a lot more about C2 programming than I do.
I don't know if the particle collision was never intended to be there and has now been removed or if there is just some bug that has come to life - I hope it is just a bug but then again if particles can be speeded up/ generally improved by removing collisions then that would probably be for the better (after all their main purpose is visual effect).
I do know that sometime it is difficult to sometimes get ideas, meaning and intent across in a written forum.