RHEL Patch Repo support issue?

Hello all. I was wondering if anyone knew if RH would support my servers is I used CentOS RPM's on RHEL. I want to put in place a repo server locally so all my systems don't have to go out to RHN. Also so I can have better control on what gets installed. But I'm worried that if I start using CentOS RPM's, RH will no longer support the base OS.

I looked in the forums and FAQ and this was not directly addressed as to the base OS but only to optional packages. If anyone can confirm the support availability by doing this it would be much appreciated. And as for using the sattelite service, it's cost prohibitive right now for me so I'm looking for a lower cost solution.

Thanks!