I tried the subsurface feature for the first time (RC6) and noticed
that normals no longer seemed to have a visible effect on lighting, e.g.
testing with an object such as

sphere
{
   y,1
   pigment {color White}
   normal  {bozo 100 scale 0.2}
   // finish  {subsurface {translucency 0.2}}
}

Is this a known limitation? If so it should probably be documented
in the warning section of the subsurface reference.

Also, if I understand correctly SSLT completely replaces the lighting
model. I would have found it to be more intuitive if it were just some
additional effect (similar to a reflection block, at least without
conserve_energy). Possibly by defaulting the SSLT contribution with
a diffuse of 0 unless an explicit diffuse appears in the subsurface
block (in which case it would be physically correct, but optional, to
use diffuse 0 for the old model. Not sure if this is feasible, though.

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