I've been told that from the 3rd Version of Vray you can do Production with Vray RT, using CUDA. But I can't get its settings right for a good output image, it looks way better using ADV but i'm into animation so it takes a lot per frame. Around 3 minutes and 30 seconds if using RT.
I use Iray, and when I render, I have to set my iteration up to 8000 for good quality image. but when it is about creating animation. sometimes even 250 iteration is enough.
Outside rendering : 250 iteration
Inside Rendering : 8000 (if picture is going to be used for printing)
we also built a render farm which is GPU based. http://www.kibrit.com.tr/gpu-render-farm/
take a look