Passed the RHCE back in 2006, at the time was spending the days (and many nights) running high end RHEL systems. Stability wise everything was great, except issues with EMC drivers and booting from SAN. These were ironed out by vendor support - which is why it can pay to have that level of enterprise support; it just depends on your environment.

These days, I use Ubuntu everywhere including here - http://hackertarget.com. It is just easier to quickly get up and running (not because its Free I could be using CentOS).

So good job Red Hat, and good job Ubuntu!