Having instructed at both the PDS and the Tire Rack SS school, I can say that there are some significant differences between them. There is no doubt in my mind that that our PDS is a more extensive and impressive experience, just in terms of the seat time involved over several days, but it is proportionally more expensive as well. There are some other key differences between the programs that I can think of as well:
The kids drive their own cars in the TRSS school, their daily drivers, including beaters, compacts, station wagons, etc. You don't usually have that at the PDS, unless the kid is lucky enough to own a Porsche at a young age. There is something to be said for exploring the limits of your actual daily driver rather than mom or dad's Porsche.
The TRSS program is more focused on safe street driving than the PDS, which has a performance driving thrust that is not present in the SS school. There is more of a "defensive driving" focus that doesn't exist in the PDS. When was the last time we had an 18-wheeler come down to the Q to demonstrate the limitations of your car's visibility to a trucker when traveling down the highway, changing lanes, etc.? (The answer is "never.") We don't talk about the challenges of distractions to the driver, be it the radio, iPods, phones for talking or texting, or just the simple cause of too many teens in the car getting jacked up on each other's energy, etc.
While I think we cover vehicle dynamics that pertain to street safety fairly well in the PDS, with some of our exercises being exactly the same (threshold braking, skid pad, slalom, etc.), we don't concentrate on trying to impress youngsters with their vulnerability on the road in the same way. Our program goes beyond the basic car control skills for safety's sake and gets into the basic aspects of performance driving, preparing people to go faster in non-street situations like AX and track driving. This is totally absent from the TRSS.
That said, since kids will be kids, as Dave pointed out, and may tend to push the limits at every opportunity, this might be considered a shortcoming of the TRSS. You can't just "scare them straight" by talking about how much jeopardy they are in while driving a 3,000 lb. hunk of metal down the road at 70+ mph, you have to give them an alternative to street racing. If I had a teenager, I would definitely choose the PDS over the TRSS and do the "scared straight" stuff privately, one-on-one. Then I would try to encourage them towards autocross as a pastime, in the hope that it would supplant their urge to test the limits on the street. When I think back to the days of my youth, when I was immortal and did some crazy stuff in cars and on motorcycles, I can't help but think that an outlet where I could drive like my hair was on fire in a safe environment would have helped me resist the temptation (and the peer pressure) to explore such activity on public roads. I know for sure that if I had attended something like the PDS when I was 16, I would not have ended up backwards in a ditch on Carroll Canyon Road in my dad's '67 911S because I didn't know what trailing throttle oversteer was all about.
That's my $0.02. YMMV, since kids are all different.
TT