I'm a huge fan of the KW's, they will be a part of any future builds I do. I can't say I've fiddled extensively with the damping, beyond chasing my tail a bit..... when I put the CN36's and Fuchs on the car looked a bit funny, too low in the rear and high in the front. Of course the 10 minute solution was to lower the front:
This setup left with only about 5/8" of free travel in front before hitting the bumpstops. Impressively enough I was able to tune out the resulting bounciness with the shocks, but it created some strange dynamic behavior.
Once the light went off and I actually checked the free travel I went to the trouble of raising both ends of the car and re-tuning the shocks based on a few drives on bumpy roads. I wouldn't say I've sharpened this to a very fine point but am a believer!
With the current setup (rubber stock bushings all around, SC sways front and rear, and 19mm/25mm torsion bars) the car absolutely devours large bumps and potholes and has great chassis control. The damping characteristics of the KW's are miles ahead of the bilsteins I have on the Rot Rod. In that respect the adjustable damping is not the only advantage.
Are they expensive? Hell yes, but a good value IMO. There are just so many possibilities and variables that you can choose with the 911, different weights and setups and spring rates, having the ability to truly dial the suspension in to your combination is a huge, rather than having to deal with a one-size fits all setup.