Here's the Sponza scene done in HDRI with the St. Peter's Light Probe (HDR file). I rendered this in 22 minutes at 1200 x 1600! It has the look of a volumetric scene, but as you can see the HDRI lighting does a very good simulation of that effect- with an incredibly faster render time. Unfortunately- these image posts- like this one- are very COMPRESSED and do not show the much more beautiful soft gray scale and shadow detail that I can see on the original Vue 5 render. So you are NOT seeing the quality here... As you can probably tell by now- I am TOTALLY sold on the HDRI (Image Base Lighting) concept. I'm probably going to be doing most of my Vue images with it in the future- because of the beautiful lighting effects and FAST render times. BUT- all HDR files are NOT the same! The St. Peter's Light Probe is one of the BEST I think because it is extremely well made. Other HDR files do not render as well, in my opinion.