Subpar post DOF

Support Compositing and Post Processing
1
  1. hard transition from sharp to blur
  2. No blur in front of focus point
  3. Ghosting (like blurred and sharp images gets blended)
  4. Blurred area can have a sudden hard edge

I used the Defocus node and am interested to learn about other ways, if it’s possible to get better looking DOF in Blenders compositor. I know post DOF is limited to begin with, but this is a lot worse than what other compositors can do.