I too, like my colleges, am opposed to a 5 year C&B warranty.  If I'm to provide a warranty on the C&B work what warranty am I given by the patient that they will maintain good oral hygiene, keep a balanced diet, keep their dental recall appointments, stay away from prescriptions that cause dry mouth, monitor any bruxism habits, never have any trauma to the tooth, etc, etc. How about patients that live in nursing homes or retirement communites and have decreased manual dexterity?  What about patients that move? Also, what warranty are we getting from the lab that the crowns will last 5 years?  We don't make the crowns, and we can't control the patients habits.  

I myself have a crown, but if it fails in 5 years, I accept that the failure will likely have little to do with the dentist that seated the crown.  Also, if the dentist works for a community health center should the health center have to cover the cost of failed crowns?  Could this lead to a decreased rate of crown placement in patients that the dentists feel will not be able to maintain the oral hygiene or protective actions necessary to retain the crown?