I have been tinkering mhaze's Rock study .tgd, not really straying too far from the original, other than color and fake stones. Also used Jordan's Basic Stars background (doubled the luminosity factor), lowered the blue atmo density and tossed a planet out there. I first rendered with Path Tracing off it whipped out in just over 30 minutes. This was done with PT on and it was over 11 hours in the render. That's over 20X the time. Wow. But is it worth it? Yes, but I'd sure like to see become more reasonable, like 2 - 3 hours instead. Oh - almost forgot: I used Matt's render group with no changes other than PT on.