My opinion (for what it's worth) is that I've driven high power cars for nearly 20 years, everythin from Morgans, to XJS, TVRs etc. I have a clean license, I've only every had one speeding ticket and that was 10 years ago. I've had two accidents, one of which was my fault (No else involved!). The second accident which wasn't my fault, was caused because of a pile up on the M42. A lorry side swiped a car three cars ahead of me, the side swiped car bounced the car in the outside lane into to barrier which then came back and hit the car one ahead of the car in front of me.
The car in front of me hit that. Luckily I had enough space to stop, just. I came to rest about three yards behind the pile up.
Unfortunatly a nice girl in cirtroen BX behind me was changing the tape in her stereo and rear ended me at 60ish. Shunting me forward into the rest of the pile up.
Luckily for me, the driver in front saw I had stopped clear of him and the girl who hit me, just before she hit, also saw I was stopped clear of anyone.
It was her insurance company that claimed I had hit the original pileup thus attempting to claim knock for knock damages. If it hadn't been for the honestly of the guy in front of me and the girl behind the lying insurance company would have gotten away with it.
If I'd had the roadhawk installed (OK so it didn't exist 8 years ago) I'd have had evidence of no fault on my part.
Personally I think that the chances of it being detremental to myself is far less than it proving that the guy I just ran into the back of just pulled across from the outside lane and slammed on his breaks looking for a whiplash claim! (hasn't happened, but at the moment there's a emidemic of this scam going on i the Birmingham area!)