Will the Procedural Textures noise depth issue be limit with very small noise size on very small objects?
You can just alter the texture coordinates itself to fit a smaller scale (mapping node in Cycles and the mapping panel in BI), as increasing the noise depth will eventually lead you to floating-point errors if it gets high enough.
I had the Blender Clouds texture on object 0,01 m
noise size 0,0006 and Blender crashes when i go from noise depth 20 to 21.
Same story with LuxRender.
The texture coordinates helped, i went from scale 1 to 0.00001.
By scaling the noise size with 100 000 i was able to keep texture look and rise the noise depth from 18 to 20 in LuxRender
without crash.