Awesomeness!!!

Test from my iPhone....

OK, enough with the Vray / MentalRay battle.....

OK, enough with the Vray / MentalRay battle.....

As far as Real-time goes Mental Ray wins.... because in the Unreal world it provides the most compatible texture in MAX for import into the game engine and as for our production team typically importing more than 20,000 static meshes, that ends the debate. 

Personally, Mental Ray wins in every other aspect of rendering as well.  We have had several shootouts between the V and the M renderers several times and it is always a draw, even when one side or the other has a more experienced render jockey. In the end when juried by the people that are clueless as to even what a renderer is; THEY CANNOT TELL THE DIFFERENCE.  (....that is especially true to the one person that counts, our client.)

Now if your creating what I call "Cheaters" 3D by rendering several stupid long images and then photshopping them together... then Vray your little hearts out. BUT if you create "Real" comprehensive 3D environments that can be directly imported into a 3D engine, then Mental ray is your tool.