Chrysler recommends front wheel bearing replacement after 12(!) hours of on track use in ACR Neons, while street driven cars would use up the bearings in 60 - 90k miles. I've seen Neons lose a wheel at the track from bearing failure. Not pretty!
So... back to the "green" bearings. Yeah, they'll last a long time on the street before you see one fail, but it will fail, and as I said I don't want it to be on my car.