I would be inclined to see it the other way around. In most of the places where I have worked, there are enough people to provide support and build custom packa

I would be inclined to see it the other way around. In most of the places where I have worked, there are enough people to provide support and build custom packages for the CentOS that paid Red Hat support makes little sense. As to why you would use it vs other Linux distributions? It's well supported by commercial software, server hardware, and there's a large pool of people with Red Hat certification which is directly applicable to CentOS. It's also pretty mature and not prone to sudden changes. I would imagine that most RHEL customers are to be found in more conservative sectors of business, but that could just be my personal biases :)