The one really big downside to my lighting setup is that it chokes on most transmapped hair - this is not all that much a fault of Poser though, I think that's common in GI.  I just set hair to be exempt from raytracing, too much time required otherwise.  Partly this is how complex Poser hair models tend to be, with many planes of overlapping transparent polys.  Probably I need to start doing my own hair models as well.

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