Tesla card with same number of core and clock speed of a geforce , are 4x faster in double precision . I'm dont know pyrofx 2.0 use double precision or not.
iray included in Subscription Advantage Pack for 3ds Max Design 2011 . Here's a link for those interested in render time and quality
http://www.the-area.com/blogs/shane/fun_with_iray_and_physx