Your materials are just spot on and amazing; the surfaces are perfectly textured, and very detailed. Indigo is a great render engine, as evident by this scene. The lighting is beautifully rich and realistic, and the atmosphere is dramatic. Very cool work.
Yes, I may have to look at Indigo in the near future. Currently, I'm Alpha testing another unbiased engine for 3dsmax called Corona, and it's pretty impressive. Not quite ready for prime-time yet, as it's still in Alpha, but really really fast for unbiased CPU rendering, and features some impressive algorithms that produce very good results. I'll keep you posted.