I haven't had a problem with mine (knock on wood). I put them in back in '03 and have put approximately 10,000 - 12,000 miles on them without a problem. They got me up to the 'Nats and back in '05 - a round trip of about 2800 miles. I've changed out the pumpkin numerous times (probably 3-4 times) since the Green bearings have been in the rear end, too.
I have heard there is an alternative bearing to the Green bearings that uses the same kind of principle in that you don't need to set side load thrust clearance if you remove the axles (in order to swap pumpkins for instance). They are supposed to be good for street use but I just can't think of the name of them off the top of my head.