You should get packages for RHEL from Red Hat Network. In the interest of maintaining utmost integrity of packages, Red Hat only patches packages with serious bugs (ie, security), and backports these packages to the main version of the specific software.
If you want to run the latest and greatest bleeding edge Apache, you're pretty much on your own. Red Hat won't provide any support for packages that were not installed for that specific RHEL version from RHN.
While packages for other distributions like Fedora Rawhide may install cleanly, those packages were not "blessed" for RHEL. If you're running RHEL, stick with the packages provided by RHN.