From top down this looks good, but from waist high, you get horizontal "stripes" from the fog strips.

I thought originally you were using vertically oriented polys, and adjusted height with the shader? This might work better from a typical render perspective.

Render times though are really much too high for practical use. I even tried removing ever other poly layer starting with the bottom one (Which really wouldn't be needed anyway) and rendertimes were still problematic.

 

Way too many people take way too many things way too seriously.