I call bullshit on Fran. I work with OEL and RHEL everyday at work. I have done a bunch of installs of RAC on both platforms over many years and support many clusters both in house and at customer sites. There is hardly a difference between the two distro's at all... the main difference is some tweaked entries in /etc/sysctl.conf and their "custom" kernel, which will more than likely turn out to be a tool they use to lock you in to their hardware/software stack even more. Oracle software itself isn't terrible, RAC is a nice, speedy database but as a company they're despicable. Before we made the giant, multi-billion dollar enterprise wide switch to OEL, they blamed any issue on RHEL even when RHEL support could prove it was Oracle's code that was fubar. Literally a day after the contract is signed... "oh yeah, there's a problem with our software code, it wasn't a RHEL problem after all... sorry about that, here's the fix". Even to this day with all their supposed hacking of their kernel and uber-custom sysctl.conf entry, they still blame every goddamn problem that we or a customer has on something else... hardware, network, the moons gravitational pull, etc... Their support is atrocious, filled with people who have no interest in actually fixing your problems and quite frankly are well... idiots. If I ever have a hand in any future business decisions for my current company or any other company I ever work for, I will always vehemently recommend against Oracle because their business model is a nasty mix of vendor hardware/software stack lock-in and extortion.
Fuck Oracle. At least RedHat appreciates your business, is uber-helpful if you do have a problem and really quick to fix things if you can prove to them through kernel dumps or some other means that the OS is having an issue.