I'm testing your tool, and so far it is great. The 2D sectors works perfectly and they are allowing me to make my test level way faster than placing texturized planes. There is just one problem, the 3D sector only supports one material and there is no option to change it, is there a reason why? or do you have any plans to add support to that? (I'll rate this tool once I'm done with my level)
Edit: Brushes and 3D sectors are sharing the same material with the Ceiling.