The final render took around 9 hours, but I think I bumped up the pixel samples probably a bit too much for the PBR. Pixel samples 20 x 20, image resolution 1600px x 1080px.
Diffuse limit 2
Color space: Gamma 2.2
This topic on the sidefx forum helped me a lot to achieve this render.
The most important light in my scene is the environment light that has an HDR environment map attached to it. I recommend taking out any walls or objects that may obstruct the light.
Peter Quint has a tutorial on this. Check out his videos and his scene files.
System specs: Intel Core 2 duo, quad core q9950- 2.83 GHZ ; 8Gb of ram.