For SCCA or NASA, check and see what classes you plan on running in before putting any full suspension on your car. You will be limited to classes by the modifications you do or do not have on your car. If you're not careful, you can modify your car right out of the most popular and accessible classes available to your vehicle.
As for street/track, I am sure the Hotchkis is an excellent overall setup. The testing shows this. However, I'm unaware of how much adjustment can be done with the kit. In fact, as serious as Hotchkis seems, I am sure they have (or will have) a fully adjustable setup. For serious track use does not necessarily imply performance alone. Serious track use implies a very high level of adjustment in nearly every component of the suspension. It would have to be altered depending on the track and the conditions at the time for the specific attributes the driver prefers. This applies to autox as well.
The numbers in the article are very impressive for a Celica... a stock Celica... especially a stock Celica with a suspension kit in that price range. Remember that pulling over 1G is not necessarily a big feat for any competitive track car with suspension and tires to match. It's quite common actually. Pulling over 1G on a car that you can then drive home is outstanding. The Hotchkis Celica and what that streetable suspension has achieved is the real feat.
btw- Anyone know what brand and size tires the Hotchkis Celica was using for the testing?