You could also try pulling the key in an ‘alpha node’.
In the key node (3) add loads of saturation and Radius blur and actual Blur.
In the output node (2) check the invert box in the post mixing part of the key page.
It just takes the strong key, not the blur or the saturation.

I agree with comments about the NR – I’ve only ever used it on RED footage successfully. Anything else I use Neat in FCP.
~M