I can come up with all sorts of ways to test the odd edges of render engines ... the issue is do they matter for the use most users will put them too :) Let me put this a simply as I can. Micropolygon displacement is far more important to me and those I work with than being able to selectively show or hide items in reflections. I am also not at all sure that it isn't something that can be done in Firefly :) However, if such abilities become important then I am sure they exist in the Shade engine :)