My experience of thirty years tells me very few system are pure. Because developers like to push hard into newer code bases even production server often contain base language libraries (perl, python, java) that are from no-vendor sources.

Then there is the question of the support it self. I worked on the Dell Linux/Complex systems support team. I experienced some crazy support problems. Thinks like a Dell server with an multi terabyte Apple drive array running CenOS linux. (This was a four letter government agency.) Yes Dell did support it.

If you pay your support money, vendors will bend over backwards to help you fix you issues. Including, contacting another vendor on your behalf to resolve the problem. So, support is worth the money you pay. But it’s not cheep!

Also, I’d rather a company use CentOS rather then pirate Redhat or play the entitlement shell game.

A CentOS user will install rpmforge, and then the sky’s the limit. RH will not support these; so migrating to RHEL also means the user should be very careful with package selection.