I was playing around with GPU particles in VR realy cool. I couldn't find a way to trigger stuff from collision events. I wondered if it is currently unimplemented in the GD4 beta but was also thinking that it could be a 'no no' because of optimization issues when it comes to the goal of using the GPU for collisions and triggering CPU intensive sounds or creation of objects. Let me know if I'm right or missing something!
In my case I was shooting little balls by manually emitting particles and I wanted a sound to trigger on collision with a GPU collision box.