For a few reasons but mainly, they're illegal, they're not overly comfortable for NSW roads, and just complete overkill for the use of the car.
But they really are great coilovers, one of the best you can buy.

Since my plan is to have this car for a number of years, I'm trying to be sure any modifications I make can be engineered, and not noticed by your average cop.

jsnhrl
Why are you changing the KW's?
And I had the same thing happen to me during the QLD nationals - hit a bump which sent my wheel into the suspension because of those elongated holes!

Yes this can be a problem, especially if you have wide front wheels and the tyre is very close to the spring.
However there is an easy fix to stop that happening:
First set the camber exactly where you want it, torque up bolts, then tap in a wedge and wire it so it can't fall out.
 
They can easily be made from 10 mm thick aluminum plate, or strip. Concave side faces in to the coilover body.
With these you still retain the ability to fully adjust camber.

 

Reddtarga
Yes this can be a problem, especially if you have wide front wheels and the tyre is very close to the spring.
However there is an easy fix to stop that happening:
First set the camber exactly where you want it, torque up bolts, then tap in a wedge and wire it so it can't fall out.
 
They can easily be made from 10 mm thick aluminum plate, or strip. Concave side faces in to the coilover body.
With these you still retain the ability to fully adjust camber.

That's a great idea, someone should make a few of these and sell them.