Just wanted to say this thread has been very helpful.  I, too, have been having problems with transmapped hair looking strange.  I think Poser 9 must handle materials differently.

One thing I've found is that I have to change the diffuse color to something matching the hair.  It can be white in older versions of Poser, but for some reason, it shows through with Poser 9, making the hair look bizarrely striped.

I would like to use IBL more, but it seems I don't have enough memory.  Poser chokes.  (Reminds me of the old days of Poser 5.)  I'm running Windows 7, 64-bit, with 12 Gb of RAM.  Would using 64-bit Poser Pro instead help?  Do I need more RAM?  Do I need to render smaller images?  (I like to render at 1600x1200, or thereabouts.)

I'm using bucket sizes as small as 4, but getting a memory error suggesting I use smaller bucket sizes or adaptive something or another.  No idea what the latter is, or how to change it.