I have about the same time in Linux as you but how I found out about SL was due to the delays CentOS has been having. Previously, the CentOS releases were not

I have about the same time in Linux as you but how I found out about SL was due to the delays CentOS has been having. Previously, the CentOS releases were not far behind RHEL releases as far as timing. But when 6.0 failed to show up I visited the CentOS forum. For whatever reason that only the internal developers know, announced milestone after milestone were delayed. The chief complaint about CentOS has been the lack of openness or transparency with the devs. Numerous offers to help and contribute to the project have not been accepted. With little feedback or request for help, users became antsy if the CentOS project was dead in the water. That's where Scientific Linux seemed to have found some new users when they were the first out of the gate with a version 6 based on RHEL. While it's great that CentOS 6.0 is out, maybe the better question is to ask why not 6.1 which was already released by RHEL some time ago (May 19th) that addresses some security issues. I used CentOS quite a bit but have moved off to distributions as I'm happy to pay for some software and contribute to other ecosystems where there is an openness to them.