The CG-Lock web site is loaded with testimonials from professional drivers and race car drivers, attesting to the benefits of the CG-Lock. I had my testing unit installed in my family car, so I didn't get too crazy with it, but I did try some rapid cornering, and other maneuvering that would have normally left me feeling like I was floating in my seat. I absolutely felt more stable, and in better control of my vehicle. I was able to quickly release my belt in order to exit my vehicle.
I also experienced another benefit. As many cops do, I have a sore lower back. With my CG-Lock cinched up snuggly, I was pulled tighter into the lumbar support of my seat, which kept my lower back supported. I was able to drive longer distances with much less lower back fatigue and pain. For me, that alone would make the CG-Lock worth the price (about $42).
I experienced a couple of drawbacks. First, once the CG-Lock is cinched tight, it's not that easy to loosen. You can release it totally by just hitting your safety belt release, but then your belt is all the way off. In order to return the belt to its normal, more relaxed fit across your lap, you really need to release the side lever on the CG-Lock, and I found this a little difficult to do without fumbling with it. In order to remove the slider, thus disabling the CG-Lock during those times you don't want to use it, you need to pull over and use two hands to remove it. That can get to be a hassle after a while.
The second issue, and one that several other reviewers have mentioned, is that the CG-Lock--although compact--does add some weight to the "tongue" portion of your safety belt buckle. If you're in the habit of hitting your belt release and just letting the belt retract on its own, you may experience a difficulty with the same practice while using the CG-Lock. The added weight sometimes makes it necessary to "assist" the belt to its retracted position.
These are minor annoyances though, and once you get used to compensating for them, the added benefit of the CG-Lock far outweighs the hassle. This is especially true if you engage in higher stress driving while on duty.
One caveat: In order for the CG-Lock to fit onto the safety belt of a Crown Vic patrol unit, a slight modification needs to be made to the edge of the safety belt buckle. I didn't get a chance to try this for myself, but clear instructions are posted on the company website, and it looks like a relatively easy modification to make. If your department administration or risk management people are squeamish about modifying the restraint system of your vehicle--even a little bit--then you may not be able to use the current configuration of the CG-Lock on Crown Victoria patrol vehicles. The company is reportedly working on a Crown Vic-friendly revision of the CG-Lock.
I found the CG-Lock to be a useful addition to my safety belt system, and I'll continue to use it. I would also recommend it for use in driver training vehicles.
Stay safe, and wear your vest (and Buckle Up!)