I've read about them before, and I recall hearing good things about them from the Viper world.
Personally, I think the GT is so uber-docile that it doesn't really need it. I suppose a flash downpour could be scary, but no TC will change the character of the rubber you're riding on. If I read their site correctly, traction is gained via cutting spark to reduce engine power. That could be a good or bad thing. Some traction control systems are just intrusive if they drastically alter the power you're expecting.
The "active handling" system from Chevy ( :willy ) is a good example of a system that combines a traditional traction control with selectively applied braking to keep you safe without killing the power unprepared. I'd never drive a high powered SVT Cobra with TC on, as even on the lowly GT it simply makes the car unpredictable...