newgsrdriver just reminded me....when I was in the market for my GC+koni yellows, I had the opportunity to purchase the "new" Tein SS for just a little more than my current setup. The main reason I ended up getting the GC's and Koni yellows was that I saw practically every bay area autocrosser running this setup (of course with custom rates and valving) and figured it was the more proven product.
Of course now there's a backlash against pricey custom GC+koni setups, and more and more folks are running the "true" coilover setups.
In my opinion, the main advantage of the GC/koni setup is that you can service them fairly quickly and painlessly. I haven't heard much feedback regarding Tein's customer service; Zeal USA seems to be pretty prompt on service calls but those are a class above the Teins.
Shingo