Indirect Lighting vs. HDRI

After I finished my latest image, Late for Class, I was talking to someone about how long it took to render.  My friend usually uses HDRI, or IBL lighting for his pictures, and it is much faster than using Indirect Lighting in Carrara.  Indirect Lighting in Carrara is so slow, it took Late for Class 6 hours to render.  That is pretty nuts.  An HDRI light would probably have taken just a few minutes… an hour or less.  I wonder how different it is, though.

I am thinking of re-rendering Late for Class with an HDRI light instead of the indirect lighting to see how it turns out.  In order to get the proper lighting, I am theorizing that I could get an HDRI map from rendering the scene again without indirect lighting, and maybe without the characters.  Then I could apply that as the HDRI light and see how it compares to the full indirect lighting.  If I have time, maybe I will try it and post it.