I think that current sharpening/blurring (S/B) implementation in VFB is not very useful, you can get the same and most often significantly better results in post. But since Corona has access to raw 3D data, then why not to use this to its advantage? If Corona could use DOF and z-depth data to enhance its S/B algorithms, then it would be big win. I imagine it could be something like couple additional parameters to current S/B UI - "DOF influence" and "Z-Depth influence", where if you increase DOF influence parameter it would sharpen focused areas and blur de-focused areas more. Same with z-depth influence - sharpen foreground and blur background more.
I know that z-depth based sharpening/blurring can be easily achieved in post, but i think DOF based sharpening would be truly unique feature in Corona.