I've been using these on my daily driven '95 Impala SS for years now, with no problems. They improve stopping distance and have a better "grab" feel to them. I no longer have the warpage problem I had with the stock front rotors.
The only person that I've heard from, first hand, that had a failure (Stress Cracks) with these was using them for auto-cross on his Impala SS. You will go through a set of pads in a few hours doing that and I can understand the cracking. He has since upgraded to 13" BAER Brakes. But for a daily driven car, the Auto Specialties are very good "stock replacements" only. If you want the high perf stuff you're going to have to up for the high dollar, large diameter deals.
I'm putting these on my '66 Malibu as well. I'm doing a four whell disc brake conversion on that car right now.
EDIT: That reminds me. The brake pads I like to use are Performance Friction (PF pads). They are the ones in the dark blue box, semi-metallics. Stay away from the Raybestoes "Brute Stops" They give off excessive brake dust and will waste a brand new set of rotors in half the time of regular pads. The parts stores usually try and push these on you (for obvious reasons) but demand the PF pads, they have them in stock. If not, walk out.
San Gabriel, CA
57 Bel Air
95 Impala SS
[This message has been edited by Mondo454 (edited 12-13-2001).]