Comment Update & security responsiveness (Score 5, Insightful) 666
By and large the CentOS team do an excellent job with the distribution - but it's a volunteer effort and there have been some notable times lately when important or security updates which have been shipped by Red Hat run late with CentOS, sometimes by a considerable amount of time.
If the CIO wants CentOS over Red Hat, he also needs to be prepared to accept the risk of delayed updates, no guarantees to updates or bug fixes and that one annoying time a particular server suffers an obscure bug, there won't be a vendor to go back to for obtaining a resolution.