Progressive blur gradient controls

Would be awesome to have full gradient control of the progressive blur map. Right now its essentially a linear gradient with only two knots. I would suggest treating this feature similar to the gradient picker. this would allow for 3 key features:

1. the ability to change it to radial would be fantastic.
2.  the ability to add knots to the gradient would really open up a lot of possibilities
3. being able to quickly reverse the order of the knots would also be a nice timesaver

I also saw someone else suggested adding a custom image map option. That could also be pretty sweet, I would imagine it could be a third blur type: Uniform, Progressive, Image.