When Adobe removed the vector paint plugin from AE a handful of animators complained that they couldn't create a specific type of stylized animations, but i have a completely different problem with this. I loved painting directly in comps for the purpose of plugging Matte holes manually. I used a layer solid with vector paint - this was a perfect alpha matte for the holes/specs. This workflow was a LIFESAVER in many comping situations. I've been trying to find an alternative in CS5 but so far I'm hitting a wall.. any ideas?
While I may not be understanding your question completely, I have been using CC Vector Blur to eliminate various imperfections in layers.
I just create a solid. Mask the area I need to fix and apply CC Vector Blur. I apply the blur amount (20), leave vector map at none, and change the property to alpha. Map Softness at 42 if I want the alpha to blur.
Then I add the layer as an alpha (inverted)layer or use Set Matte if multiple mattes are needed at different levels.