Just got back from the states, so I still have a bit of jetlag (man I hate that).
But anyway, someone suggested I should take a look at Mesh Fusion, which is a really interesting tool that does approximate CSG with subdivision surfaces.
This made me want to try to see if I can get my CSG algorithm to work with subdivision surfaces, which I never tried out.
So here's my first attempt at performing subdivision surfaces on a cube mesh, about half a days work.
Next on my list of things to do is fix some t-junction issues on the final mesh that pops out of the CSG process. I need to get the whole plugin in a shippable status, after that I'll continue my research on subdiv.