. The behaviour of DR is a bit special and it's doesn't recognize the event to hide the objects in the DR nodes. We'll try to solve this issue in next versions.
About the use of external proxies, it's not supported in Forest by compatibility. The plugin is designed to use many types of objects: meshes, proxies or even RPC, and it must work with multiple renders as VRay, Mental Ray or Scanline. So, we prefer to use a common interface for all these posibilities, picking the source object from the scene.
Also, as alternative to the proxies workflow, remember that in Forest you can use any high-poly mesh from the scene, getting the same render performance (sometimes better). This saves you to handle tons of external proxy files and references, what may be useful in some situations.