"Why pay for RedHat RHEL if there's CentOS?" somebody may think.

One of the answers is here. Just check it out - most of the vulnerabilities RedHat fixed during one day. For example, "Non-Browser" applications (e.g. Samba, Sendmail, OpenSSH, Gaim, evolution) had 16 issues, with average fixing time 14 hours, and 94% of issues were fixed during one day. (Read more...)