Yeah, but it depends on how you want to animate them. If they're not moving much individually, that would be fine. I might use this for distant asteroids where you wouldn't notice it so much. This probably makes more sense for distant stars. I'm using this approach for distant asteroids and stars in many Space Tommy shots.
If you want them to rotate individually, making multiple layers is better, but you can minimize the number of individual asteroids by cycling their positions. In Space Tommy, for example, I think I'm using two or three sets of asteroids in most of the shots, and just cycling their positions as after they move off camera. I'm not animating the asteroids themselves because Moho Physics is handling that part for me, including random collisions. I'm only animating the positions for two or three groups.
Note: I should verify exactly what I did. Space Tommy was made 10 months ago, and I've animated so much stuff since then that my memory about the Space Tommy setups is a little fuzzy. I try to keep my setups pretty simple to avoid problems, and from what I recall, creating the short went very quickly using Moho 14.1, and I didn't run into any major problems. If I have time, I'll check those setups and let you know exactly what's going on in them.
Particles is another good way to go because, with the right settings, they can stay 'on' for a limited time and disappear when they go off camera. They don't need to pop off...they can fade out just before they disappear.
Not really related, but I used Moho Particles for the sparkles coming off the gold asteroid. The sparkles in the coffee machine were made using Scatter tool, though. So, I guess I used a lot of different techniques. I really should make a BTS for Space Tommy before I totally forget how it was made.
