I always use VSS with PP2010 and fail to have a problem with wash outs.  There are numerous factors that figure in when using IDL with P8 and PP2010.  Particularly PP2010, if you are using VSSPR3, you will need to change the Gc node to 1 when rendering with Gc on.  However, the latest iteration VSS (VSSPR4) has auto Gc, it will determine if Gc is used in the render settings and will adjust itself accordingly.  Lighting shoud be kept to minimum depending the scene requirements.  Sunny days, for example, should not require multiple light to illuminate the scene.  A good, self-illuminating skydome (BB's envsphere) should provide adequate lighting with IDL.  Diffuse_values for materials should not be set to 100% (1.0), they overwork render calculations because Poser thinks that everything reflects diffusely at 100%.  Lighting intensities do not require 100%.  I can get excellent daytime lighting @ 75-80% using Gc and IDL.

You really need to experiment further with settings on all levels.  The old mentality governing earlier Poser versions, no longer apply to the P8 and the Pro versions.  You have to rethink everything placed within a scene.