lOOk at fr-63 the blob... can you see the reflexion the ship is crossing? you want that? than use rendertarget. its nearly a true mirror. for doing this as real true really mirror maybe one day the custom raytrace stuff can help
at all if you do right directing to the scene with rendertarget you can do reflex stuff.
if you have ever done any type of realtime stuff, you should know that there are many ways to create your major fx. my tip: use your creativity instead having an op that maybe not needed (maybe)..