First, here is the obligatory line: sorry for not posting recently, have been busy.
Yesterday I pestered Mental Ray a bit, using many things known to slow it down: Global Illumination, Caustics, light radius....
With just a single object on a floor plane and one spotlight, this took over ten minutes to render. And you know what? I and seriously considering adding real depth of field. Oh, and then maybe animate it and add motion blur. While I'm at it, I should then also up the resolution from 720p to 1080p. Still, that will probably not half as bad as the radiosity render a fellow student of mine at ACCAD had running for a couple of weeks before it finally produced a very grainy image.
Why am I messing with GI? I took over a course at PRATT this semester: 3D lighting and rendering.