I don't use all the distributions supported by the script, so I don't always know the compatibility tricks such as "Centos 3.4 is fully compatible with RHEL 3", allowing yum-pull to pull down any rhel3 repositories for centos 3.4 as well. If anyone knows of compatible distributions like those, I can do the work to make yum-pull smarter.
Maybe you could consider http://taolinux.org/wiki/Main_Page when searching for compatible Distros. We use it as a replacement for RHAS on low priority servers and workstations.
Regards, Thomas