Yeah, in-place upgrades between CentOS releases are not really supported, just as they are not really supported with RHEL. However, this also comes with a perk

Yeah, in-place upgrades between CentOS releases are not really supported, just as they are not really supported with RHEL. However, this also comes with a perk. CentOS releases are generally the "current" release for at least three years, as opposed to two with Debian. Also, major releases are supported with critical security updates for years after they are no longer current. For example, CentOS 6 will still receive patches until November 2020. Of course, whether this is important to you will vary based upon your needs. For some, the 2 year releases with an easy upgrade path between major releases will be the more important factor.