Opera, I don't think you need raytrace turned on at all just to use the fastscatter node in Poser. Fastscatter is subject to depth map shadows. Unless you mean AO, which is raytraced. Anyway, I'm sure you can include/exclude objects from certain lights in Carrara, or exclude certain objects from receiving raytraced shadows, or any shadows at all. I haven't tried it yet, but most 3D apps can do this. I know it's possible in Vue 5i for example. If not, then that's a real bummer in my opinion.