Quote - Like steering a car with your feet (possible but may produce unexpected results) it is possible to use gray chips for controlling light intensity, but I use the intensity parameter to control intensity and leave my chips white.

Color chips that are not white or black are altered by gamma setting. If you do not firmly understand what RGB 170, 170, 170 really means with and without GC, and you're experimenting with gamma as an artistic control, you may be changing more than you mean to.

Yes, this is what I'm trying to avoid, experimentation without fully understanding what is going on.

However, ArtBee wrote a Gamma Correction guide:

http://www.book.artbeeweb.nl/?p=317 - PDF on the page.

On page 31 he talks about Anti Gamma Correction and mentions this:

"By putting the light intensity in the color swatch instead of in the numericals, you do get the better image. This holds in all cases of the Material Room."

He compares one image with 100% white and 60% intensity vs another image with 100% intensity and 60% white. I'm still trying to make sense of it. 

I use .7 IDL intensity. I have a single point light @ 112% intensity in a GC-2.2, IDL, SSS scene, enclosed room. The point light specular is at 100% and diffuse set to 244,244,244. The render looks great I don't see any problems or washing out. The cool thing about this lighting strategy is I don't have to add another light just for specular. I use your light meter and both the diffuse & specular are as close to white as possible without yellow or red burning.