I would assume that the renderer in TG2 uses some kind of stochastic method, which are classically known in the literature to introduce noise into renders which is why such renderers have a pre-pass stage and take samples; would it there for be possible (Theoretically at least) to implement Bidirectional Path Tracing into the renderer to increase sample accuracy and reduce noise, meaning fewer samples would be needed thusly helping with render times.
All of the above is naturally theoretical and based on theories (Which might be way off) that I have about the nature of the renderer in TG2.
Regards to you.
Cyber-Angel