Quote - I don't see much of a speed hit so long as there isn't too much transparancy, and that can be gotten around in many circumstances by setting transmapped hairs and such to be invisible in raytracing.

There are some great tips on IDL settings in this thread...

http://www.renderosity.com/mod/forumpro/showthread.php?thread_id=2789760&page=1

There's some great info in that thread. Thanks ;-)