Also having the ability to use Piranesi to tweak Octane (make it more cartooni/artsy

This would mean the ability of Octane to export .epx files which are 2.5 d containing information about the depth and planes.
I totally agree when it comes to texturing stuff. I was thinking about one click send to octane for faster than fast preview/draft renders and the posibility to assign archicad materials to octane materials too . Blender is great if you want quality UVs and lots of other nice stuff, but if you cannot afford another 10-15 minutes in blender it could be useful to just hit a button in archicad...as im long time archicad user i can say only this...
archicad material assigning and material tool work is complete DISASTER and i can bet it is software with worst material workflow on this planet...